Release editor > removing a track resets manually changed track positions

If you manually change track position, and the remove a track, track posistions are reset.

Steps to reproduce:
1. Open http://musicbrainz.org/release/8b26b7cc-0766-4da3-94db-97920a309513/edit
2. Go to Tracklist tab
3. Change track position (first cell) of actual track #3 "blablabla" to 5
4. Change track position (first cell) of actual track #5 "nei" to 3
5. Delete track #7 "neinei" => changes made in steps 3 and 4 have been lost