The `commit_id` property name is the same as equivalent functionality in
GitHub. If the action was not caused by a commit, an empty string is
used.
This can for example be used to automatically add a Resolved label to an
issue fixed by a commit, or clear it when the issue is reopened.
Swallow error just like in #20839, for the case where there is no
protected branch.
Fixes#20826 for me, though I can't tell if this now covers all cases.