Noisy mentions from fork (useless "last updated" sorting)
Summary
If I push to my fork commits with references to the issue I see mentions noise in the original project issue. The problem is that we have to "remember if a commit SHA has already been mentioned already" (@godfat) .
This also breaks MR and Issue sorting by "last updated" (not actually breaks but makes it useless)
Also the discussion is available here https://gitlab.com/gitlab-org/gitlab-ce/issues/20527#note_15676024
Steps to reproduce
Just update your fork and issue will come up
Expected behavior
Every commit should notify origin issue only once
Actual behavior
We have a lot of mentions from the same commit from every fork
Relevant logs and/or screenshots
https://gitlab.com/gitlab-org/gitlab-ce/issues/20527#note_15676024
/cc @DouweM @rspeicher