Comment # 2 on bug 1171023 from Giorgio TOMBOLA

(In reply to Neil Rickert from comment #1)
> I think that's  because the other linux (or the "os-prober" in that linux)
> does not properly handle "btrfs" file systems.
Two os don't "handle" btrfs systems? Possible but not probable.

Anyway I asked first to openMandriva developers, here's part of their answer:
"What we tested was if OpenMandriva os-prober and grub2 would properly
recognize an OM Lx system with btrfs. This was tested and confirmed working
multiple times.
.....
.....
After fixing this issue we then discovered a different problem with openSUSE
with btrfs. openSUSE uses custom patches and custom syntax that is not
compatible with OM code. Specifically they call btrfs > xbtrfs in their patches
for os-prober and grub2."

Then it seems that openSuse btrfs is not "standard" in some way.