Incorrect measure duration after time change

As reported by Widmung: http://musescore.org/en/node/6012#comment-16651

Steps to reproduce bug
1. Open a new score using 4/4 time signature.
2. Right click on 1st bar and select 'measure properties'. Leave nominal duration as 4/4 but change actual duration to 2/4.
3. Drag a 3/4 time signature into the second bar.
4. Have second bar selected and insert 8 new measures before the second bar. These measures will also become 4/4 nominal duration and 2/4 actual duration.
5. Drag a 4/4 time signature into the second bar.
6. Insert crotchets into all the bars and you will notice that the 4 bars before the 3/4 time signature only have room for 3 crotchets.

MuseScore version: r. 3137 nightly build

(Operating System: Windows 7)