Merge ~cjwatson/launchpad:ci-recalculate-builder-constraints into launchpad:master

[Colin Watson]

Recalculate CIBuild.builder_constraints on retry

This allows us to reconfigure a repository's builder constraints and then just retry builds, rather than having to push new commits to cause new builds to be created.

[Clinton Fung (clinton-fung)]

Added an inline comment, otherwise +1 from me.

review: Approve

diff --git a/lib/lp/code/model/cibuild.py b/lib/lp/code/model/cibuild.py
index d431000..0bfc773 100644
--- a/lib/lp/code/model/cibuild.py
+++ b/lib/lp/code/model/cibuild.py
@@ -310,6 +310,13 @@ class CIBuild(PackageBuildMixin, StormBase):
             return False
         return super().can_be_retried
 
+    def resetBuild(self):
+        """See `IBuildFarmJob`."""
+        super().resetBuild()
+        self.builder_constraints = copy(
+            removeSecurityProxy(self.git_repository.builder_constraints)
+        )
+
     def calculateScore(self):
         # Low latency is especially useful for CI builds, so score these
         # above bulky things like live filesystem builds, but below
diff --git a/lib/lp/code/model/tests/test_cibuild.py b/lib/lp/code/model/tests/test_cibuild.py
index 114b606..d5b4405 100644
--- a/lib/lp/code/model/tests/test_cibuild.py
+++ b/lib/lp/code/model/tests/test_cibuild.py
@@ -68,6 +68,7 @@ from lp.testing import (
     StormStatementRecorder,
     TestCaseWithFactory,
     api_url,
+    celebrity_logged_in,
     login,
     logout,
     person_logged_in,
@@ -240,6 +241,19 @@ class TestCIBuild(TestCaseWithFactory):
         self.assertIsNone(build.upload_log)
         self.assertEqual(0, build.failure_count)
 
+    def test_retry_resets_builder_constraints(self):
+        # Retrying a build recalculates its builder constraints.
+        build = self.factory.makeCIBuild()
+        self.assertIsNone(build.builder_constraints)
+        build.updateStatus(BuildStatus.BUILDING)
+        build.updateStatus(BuildStatus.FAILEDTOBUILD)
+        build.gotFailure()
+        with celebrity_logged_in("commercial_admin"):
+            build.git_repository.builder_constraints = ["gpu"]
+        with person_logged_in(build.git_repository.owner):
+            build.retry()
+        self.assertEqual(("gpu",), build.builder_constraints)
+
     def test_cancel_not_in_progress(self):
         # The cancel() method for a pending build leaves it in the CANCELLED
         # state.