Prune outdated refs/tmp references
From gitlab-com/infrastructure#2904 (closed), we appear to have over 8,000 temporary references in the GitLab CE repository that probably don't need to be there anymore. This seems to be slowing pushes by 20+ seconds.
As part of our garbage collection process, we should probably remove these if they are older than some time (e.g. a week) because they can significantly affect performance. These refs aren't folded into the packed-refs
file, so each of them will cause an extra stat
and open
system call unnecessarily.