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
At the time of writing I am able to reproduce this problem on:
http://musicbrainz.org/release/012134c9-c19d-4b42-b9ba-c758852ea1b4/edit
but not on:
http://beta.musicbrainz.org/release/012134c9-c19d-4b42-b9ba-c758852ea1b4/edit
I assume this issue was fixed by commit 1a277938013ab6f6198618c51c19167d9d887ef7 /
MBS-4520.