A few days ago I performed a zypper up with Tumbleweed 20160422, after which
grub did not have Tumbleweed in its bootable systems. The other three systems
are available, but the fourth, Tumbleweed, should be there as well.
Today I tried to repair this with the DVD iso on a USB stick with 20160430 by
performing an upgrade.
I got an error message like:
Internal error. Please report a bug report with logs.
Details: undefined local variable or method `extended' for #<Bootloader::Stage
Caller:  /usr/share/YaST2/lib/bootloader/stage1.rb:172:in `available_partition

I can't find the YaST log on the partition with the Tumbleweed system.