R1:1cda1402c7c2

Do not publish/notify about commits which are not reachable from any "Autoclose" ref

Summary:
Depends on D20418. Ref T13277. Fixes T11314.

Currently, when you push commits to some arbitrary ref or tag (like `refs/pull/123` on GitHub, `refs/tags/phabricator/diff/123` on Phabricator, or `refs/changes/whatever` on Gerrit), we do not "autoclose" related objects. This means that we don't process `Ref T123` to create links to tasks, and don't process `Differential Revision: xyz` to close revisions.

However…