Comment # 3 on bug 933565 from Chris Ward

I upgraded with 'apper', so there is no YAST log to attach. Instructions for
reproducing the problem are ...
1) Install OpenSuSE 13.2 on the computer's internal disk.
2) Plug in a USB disk and install Tumbleweed (with ext4 /home)
3) Use the internal OpenSuSE to shrink the /home of the tumbleweed
4) Install Fedora with default options in the freed space
5) Install Tumbleweed again (because Fedora does not offer to boot OpenSuSE)
over the existing tumbleweed installation.
6) Update Tumbleweed with 'apper' in such a way that a new kernel gets
installed. I was updating from 20150529 or so to today's updates (as of
2015-06-04)
Observe that on the next reboot the system offers the Fedora boot menu, which
does not offer to boot the tumbleweed system.