Undo unavailable if moving accidental via keyboard

1. Open attached score (produced in 1.3).
2. Double-click accidental.
3. Move via direction keys.
4. Exit edit mode (e.g. click elsewhere).

Result: Undo is unavailable.

Note: If dragged via mouse, undo works fine.

Using MuseScore 2.0 Nightly Build (3a4f0bc) - Mac 10.7.5.