Merge request discussions can't be resolved when running GitLab at a relative URL

Summary

The merge request "Resolve discussion" button and checkmarks for comments have no effect when running GitLab at a relative URL. The URL used for the POST request doesn't contain the relative URL part.

If I edit the URL and resend the request, the discussion is resolved correctly.

GitLab Version: 8.11.3 (CE)

Steps to reproduce

1. Run GitLab at a relative URL (ex. https://server/path/to/gitlab)
2. Attempt to resolve a discussion or comment on a merge request

Expected behavior

POST https://server/path/to/gitlab/group/project/merge_requests/1/discussions/hash/resolve

Actual behaviour

POST https://server/group/project/merge_requests/1/discussions/hash/resolve

Added regression label

https://gitlab.com/gitlab-org/gitlab-ce/blob/master/app/assets/javascripts/diff_notes/services/resolve.js.es6#L14 looks like the problem - maybe the backend should provide this? /cc @DouweM @iamphill

mentioned in issue #20946 (closed)

@smcgivern Good find. Yes, the frontend should never be generating URLs like this!

I'll have a look at a fix

Reassigned to @iamphill

mentioned in commit 900e6cc0

mentioned in merge request !6129 (merged)

mentioned in commit 69e0e695

mentioned in issue #21854 (closed)

mentioned in commit aed07cb2

Milestone changed to %8.11

Mentioned in commit 5461a5d1

Mentioned in issue #22549 (closed)

Milestone changed to %8.12

Added ~480950 and removed regression labels

Added regression label

Status changed to closed by merge request !6129 (merged)

Mentioned in commit 56dc3e4b

mentioned in merge request !14785