Steps to reproduce

1. Remove a translation unit from a page already in translation.
2. Try to mark it again for translation.
3. Look at the Deleted translation units section.

Actual result

4. The deleted translation unit appears with unit ID -1.
   

Expected result

4. The deleted translation unit appears with its actual unit ID. For example, on the above screenshot, Recent changes’ ID is 3, which appears correctly in the diff.