[7.12.0.rc1] Branch with no files leads to 404

Steps to reproduce this error on Gitlab.com:

• Create a repository
• Add an empty file e.g. README.md to the master branch
• Create a new branch e.g. development based on master
• Remove the file (on the new created branch) via GitLab user interface (-> remove button)
• After clicking on Remove file a 404 error returns

This also affects viewing the branch via the files view.

Addition There's no need to create a new branch. Just add an empty file via GitLab ui to the master branch and delete it:

https://gitlab.com/stefan-it/gitlab-issue-1826/tree/master

Added reproduced on GitLab.com label

Looks like this is a duplicate of #1362 (closed). Proposed fix here: !1010 (merged).

Status changed to closed

mentioned in merge request !14785