[Trunk] No prompt about rewriting of measures after inserting time signature change and undo, and only applies to one stave

1. Create 4/4 score.
2. Drag 3/4 time signature onto second bar.
3. 'No' when asked "rewrite measures until the next time signature?"
4. Undo.
5. Drag 3/4 time signature onto second bar.

Result: No prompt about rewriting measures until the next time signature, and it only applies to one stave.

Using MuseScore 2.0 Nightly Build (4810) - Mac 10.6.8.