Undo paste in new time signature causes overlapping notes (0.9.6 branch)

Steps to reproduce bug
1. Open attached file: "Undo paste in new time signature.mscz"
2. Edit > Select All
3. Edit > Copy
4. Drag a 6/4 time signature to the first measure
5. Click out side the staff to deselect the measures
6. Click on an empty part of the first measure to select it
7. Edit > Paste
8. Edit > Undo

Expected behavior: Score should look the same as it did after step 4.

Actual behavior: Notice the overlapping notes in measures 7 and 8.

MuseScore version: 0.9.6.3 stable. Bug probably not possible in current trunk (I tested using r. 3548 nightly)

(Operating System: Windows 7)