Possible scenario:
1. Test fails on master; branch happens; test fix is landed on master; test passes on master but still fails on branch.
2. Test fails on official branch; test fix is landed on master, but not cherry-pick to official branch; test still fails on branch.
3. ...

This bug is to investigate how to ensure that a bug fix on master is cherry-picked to branch as well.
One idea is (feasibility needs investigation): add the test name and fixing CL in customized fields of a bug with label like "test-fail-on-branch". Once the bug is fixed, automatically post an alert to request a cherry-pick into branch (maybe sheriff-bot could help here).