Getting 502 errors on particular branches

Last night we upgraded from 8.6.2 to 8.7.2 (omnibus). We are running Ubuntu 14.04, kernel 3.19.0-51-generic. Things have been fine for the most part but today a developer noticed he was getting a 502 error when trying to create a merge request on a branch he had uploaded. The branch is not very big, changes to 3 files. Anything you try and do with that branch in the UI ends up timing out with a 502 error. Uploading another branch with the same changes also gives a 502 error so it's something related to the changes.

Here is the output from gdb : http://pastebin.com/9fmh4c0n and the output from perf : http://pastebin.com/sCj58zDZ

Please let me know if there's anything else I can provide.