Delete part of tuplet corrupts file

Steps to reproduce bug
1. Create a triplet with 3 quarter notes (half-note total duration)
2. Lasso-select on of the quarter notes (Shift+click and drag so that you get a blue rectangle around the note)
3. Del

Expected behavior: Probably the single quarter should switch to a quarter eighth rest (similar to if you had clicked on a single note head and pressed delete). The thing to make sure of is if the whole tuplet is selected then it is removed (which it currently does).

Actual behavior: Tuplet is replaced with an eighth rest, 32nd rest, and 128th rest.

MuseScore version: r. 2541 (0.9.5 hangs instead)

(Operating System: Windows XP)