Wrong highlighting of three-way-diff

1. Create a three way diff in a git repository, e.g. by trying to merge with a conflict.
2. In "Tools" -> "Options..." -> "Version Control" -> "Git", disable "Show diff side-by-side".
3. Make Creator show this diff.
   It will show the diff with a broken highlighting:
   

Instead, Creator should show only unchanged lines in normal text color, whereas the changed lines should be highlighted in a different, or even two different colors.