Creation and removal of symbolic links are not shown in commits.

Created by: kennytm

Steps to reproduce:

1. Create a symbolic link, and add this to a commit.

   ln -s whatever symlink
   git add symlink
   git commit
   git push origin master

2. Check the commit on GitLab. One will find the commit is empty, showing 0 changes.

Interestingly this does not affects the Diff tab in merge requests.