Slurs of voice > 1 become voice-1 slurs during copy and paste

Steps:
1- Open attached file;
2- Select the first measure;
3- Copy and paste to the second measure;
-> The slur seems to disappear
Actually the slur has not disappeared: if 1/8 rests are added to voice 1 the slur appears again as a voice-1 slur.

Alternatively:
1- Open attached file;
2- Select the third measure;
3- Copy and paste to the fourth measure;
-> The slur swaps to voice 1 during paste

See also #7805: Copy and paste does not preserve stem direction for beamed notes

Windows 8.1, Nightly build dc4299a