Copy-paste of whole-measure rest in incompete measure corrupts music

Steps to reproduce bug
1. Create a new score in 4/4 time
2. Right click on an empty part of measure 1 and choose "Measure Properties..."
3. Change "Actual Duration" to 3/4. Press "OK" to dismiss the dialog
4. Click on an empty part of measure 1 to select it
5. Edit > Copy
6. Click on measure 2 to select it
7. Edit > Paste

Expected behavior: Measure 2 should have four beats worth of rests

Actual behavior: Measure 2 now has a full measure rest plus a quarter note rest

MuseScore version: r. 3591 nightly trunk and 0.9.6.3 stable

(Operating System: Windows 7)