Outdated diffs in merge requests have broken display sometimes
Issue originally reported on github https://github.com/gitlabhq/gitlabhq/issues/9746 still exists in 8.2.3.
We have encountered several cases of comments disappearing from merge request UI. The comments are always linked to the obsolete diffs, usually they're new comments in the thread. One the thread is broken any new comment added to the thread will not be displayed as well. Not all discussion threads in the merge request are broken. Even if there are some broken, others are still displayed correctly.
We haven't been able to set up working reproduction process, but it looks like the Gitlab has troubles with comments being added to the merge request, while pushing new commits to the branch.
After loading the page the diff looks like this:
While the outdated diff part is correct, the current diff part lacks whole "discussion-body js-toggle-content" with diff and comments. Affected comments are also missing from the "Changes" tab of the merge request, even though they are linked to the up to date diff.