clef corruption after undo paste operation

Steps to reproduce:
1. Open the attached project file. You will see alternating treble and bass clef measures.
2. Copy the first 4 measures and paste them starting at measure 2.
3. Undo (CTRL-Z).

Result: all the clefs from the ends of measures 2-5 are now missing, although the notes are on what would be the correct lines and spaces were the clefs still shown.

The problem seems to have something to do with pasting music containing clef changes over the top of music already containing clef changes. I noticed that when deleting a range of music containing clef changes, all the measure-assigned clefs remain. I'm not sure if this is by design, but perhaps this is part of the problem.

I am using MuseScore nightly ff2b92c on Kubuntu 14.04 64-bit.