Comment # 3 on bug 1091669 from Imobach Gonzalez Sosa

After fixing bug 1085755, we have unveiled this one. It looks like we are still
relying in legacy partitioning settings when it comes to determine the list of
default subvolumes.

I am attaching a temporary patch (and a DUD) that should fix the issue for you.
It worked for me.

However, we need to finish/improve this patch, so I am keeping the bug report
open.