Undo doesn't work after changing value of grace note

1. Create score.
2. Add note.
3. Add multiple acciaccatura to note.
4. Select an acciaccatura.
5. Change value to semiquaver.
6. Undo.

Expected result: Value changes back to quaver.
Actual result: The last step before changing the value is undone (an acciaccatura will be removed).

Using MuseScore 1.1 and 2.0 Nightly Build (4652) - Mac 10.6.8.