I just updated gitlab from version 8.2.2 to 8.3.2 fbb8b6e, and now the UI in mattermost appears to be broken(ish).
All of the features still work, but the css or something similar appears to be messed up. The scrollbar is also missing.
Any help is greatly appreciated. I have no idea how to even troubleshoot a styling problem.
More Info
GitLab 8.3.2
GitLab Shell 2.6.9
GitLab API v3
Ruby 2.1.7p400
Rails 4.2.4