Beams which span two staves are positioned on the wrong staff

(Windows 7 64-bit, nightly builds: e76f2c7 and earlier)

1. Open MuseScore with the default new document.
2. Create eighth notes in the last bar of the first staff and in the first bar of the second staff.
3. Edit the beaming of the last eighth note in the first staff, so it begins a beam.
4. Edit the beaming of the first note in the second staff, so it is in the middle of a beam.
5. The beam in the second staff is incorrectly positioned on the first staff. It should be on the second staff, extending a little bit to the left of the first eighth note (in the second staff).