Example:

This CL https://chromium-review.googlesource.com/#/c/chromiumos/infra/dummies/merge-sandbox/+/810085/-1..1

was rejected by a CQ failure due to this slave build:
https://luci-milo.appspot.com/buildbot/chromeos/sentry-paladin/1709


The CL in question is to a dummy repo that does not affect any package (merge-sandbox). So it should be considered irrelevant to everything. When I look at the logs of DetectRelevantChangesStage, I don't see any package that claims to be affected by merge-sandbox. Nevertheless, it seems like that slave marks this CL as relevant:

mysql> select action, timestamp, build_config from clActionView where change_number = 810085 and build_config="sentry-paladin";
+-------------------+---------------------+----------------+
| action            | timestamp           | build_config   |
+-------------------+---------------------+----------------+
| picked_up         | 2017-12-06 04:57:55 | sentry-paladin |
| relevant_to_slave | 2017-12-06 05:19:45 | sentry-paladin |
+-------------------+---------------------+----------------+
2 rows in set (0.11 sec)