Tuplet error

MuseScore 0.9.6.3 (R3497) WinXP Media Center V5.1 SP3

I believe this bug is associated with http://musescore.org/en/node/6368 and http://musescore.org/en/node/7713.

In the attached example, select the C in the last tuplet and strike the "5" key to change its duration. I would expect an error message stating that making the change would exceed the duration of the tuplet. Instead, the measure following the tuplet is corrupted.

Now enter control-Z to attempt to undo the damage. An altered corruption is produced rather than the original version of the example.