Switch the builders to use a Python 3 recipe.

This doesn't affect the scripts themselves (as far as I know), just the
recipe engine.

Bug: chromium:1256384, chromium:1256383
Change-Id: I8d7350e2b6b31e6103cdfde0edc04f875bbe79a4
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/50186
Reviewed-by: Adam Langley <agl@google.com>
diff --git a/generated/cr-buildbucket.cfg b/generated/cr-buildbucket.cfg
index d4b6cdb..8674bba 100644
--- a/generated/cr-buildbucket.cfg
+++ b/generated/cr-buildbucket.cfg
@@ -32,6 +32,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -58,6 +62,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -84,6 +92,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -111,6 +123,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -138,6 +154,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -165,6 +185,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -192,6 +216,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -225,6 +253,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -258,6 +290,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -285,6 +321,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -312,6 +352,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -339,6 +383,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -366,6 +414,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -393,6 +445,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -420,6 +476,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -447,6 +507,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -474,6 +538,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -501,6 +569,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -528,6 +600,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -555,6 +631,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -582,6 +662,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -609,6 +693,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -636,6 +724,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -663,6 +755,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -690,6 +786,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -717,6 +817,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -744,6 +848,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -771,6 +879,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -798,6 +910,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -825,6 +941,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -852,6 +972,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -883,6 +1007,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -914,6 +1042,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -945,6 +1077,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -976,6 +1112,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1007,6 +1147,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1038,6 +1182,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1069,6 +1217,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1101,6 +1253,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1133,6 +1289,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1164,6 +1324,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1195,6 +1359,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1226,6 +1394,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1257,6 +1429,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1289,6 +1465,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1321,6 +1501,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1358,6 +1542,10 @@
       }
       service_account: "boringssl-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1394,6 +1582,10 @@
       execution_timeout_secs: 1800
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1414,6 +1606,10 @@
       execution_timeout_secs: 1800
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1434,6 +1630,10 @@
       execution_timeout_secs: 1800
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1455,6 +1655,10 @@
       execution_timeout_secs: 1800
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1476,6 +1680,10 @@
       execution_timeout_secs: 1800
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1497,6 +1705,10 @@
       execution_timeout_secs: 1800
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1518,6 +1730,10 @@
       execution_timeout_secs: 1800
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1536,6 +1752,10 @@
       execution_timeout_secs: 1800
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1560,6 +1780,10 @@
       }
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1584,6 +1808,10 @@
       }
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1602,6 +1830,10 @@
       execution_timeout_secs: 1800
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1620,6 +1852,10 @@
       execution_timeout_secs: 1800
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1638,6 +1874,10 @@
       execution_timeout_secs: 1800
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1656,6 +1896,10 @@
       execution_timeout_secs: 1800
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1674,6 +1918,10 @@
       execution_timeout_secs: 1800
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1692,6 +1940,10 @@
       execution_timeout_secs: 1800
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1710,6 +1962,10 @@
       execution_timeout_secs: 1800
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1728,6 +1984,10 @@
       execution_timeout_secs: 1800
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1746,6 +2006,10 @@
       execution_timeout_secs: 1800
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1764,6 +2028,10 @@
       execution_timeout_secs: 1800
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1782,6 +2050,10 @@
       execution_timeout_secs: 1800
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1800,6 +2072,10 @@
       execution_timeout_secs: 1800
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1818,6 +2094,10 @@
       execution_timeout_secs: 1800
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1836,6 +2116,10 @@
       execution_timeout_secs: 1800
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1854,6 +2138,10 @@
       execution_timeout_secs: 1800
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1872,6 +2160,10 @@
       execution_timeout_secs: 1800
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1890,6 +2182,10 @@
       execution_timeout_secs: 1800
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1908,6 +2204,10 @@
       execution_timeout_secs: 1800
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1926,6 +2226,10 @@
       execution_timeout_secs: 1800
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1944,6 +2248,10 @@
       execution_timeout_secs: 1800
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1966,6 +2274,10 @@
       }
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -1988,6 +2300,10 @@
       }
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -2010,6 +2326,10 @@
       }
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -2032,6 +2352,10 @@
       }
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -2054,6 +2378,10 @@
       }
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -2076,6 +2404,10 @@
       }
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -2101,6 +2433,10 @@
       }
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -2126,6 +2462,10 @@
       }
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -2148,6 +2488,10 @@
       }
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -2170,6 +2514,10 @@
       }
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -2192,6 +2540,10 @@
       }
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -2217,6 +2569,10 @@
       }
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -2242,6 +2598,10 @@
       }
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
@@ -2270,6 +2630,10 @@
       }
       service_account: "boringssl-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
+      experiments {
         key: "luci.use_realms"
         value: 100
       }
diff --git a/main.star b/main.star
index 27bc8b2..0c5339a 100755
--- a/main.star
+++ b/main.star
@@ -10,7 +10,10 @@
 lucicfg.enable_experiment("crbug.com/1085650")
 
 # Launch all builds in "realms-aware mode", crbug.com/1203847.
-luci.builder.defaults.experiments.set({"luci.use_realms": 100})
+luci.builder.defaults.experiments.set({
+    "luci.use_realms": 100,
+    "luci.recipes.use_python3": 100,
+})
 
 lucicfg.config(
     lint_checks = ["default"],