Crash when adding time signature with 0 as upper or lower numeral

After creating a score (for example in 4/4), click right on the time signature and choose "Time Signature Properties...".

"Actual Value" is 4/4. Change it to 0/4 or 4/0 (it doesn't make sens, but sometimes we can make a typographical error) and confirm changes. MuseScore crashes.

Expected result: whether MuseScore prevents to add 0 or automatically changes it for a number greater than zero (note that if we put 0 as the upper numeral when creating a new score with the wizard, MuseScore automatically changes it, so there's no crash).

Config: MuseScore f5b9240 on Xubuntu 14.10.