Comment # 28 on bug 1060551 from Stanislav Brabec

Yes, I am already searching for a libblkid level fix.

Regarding the race: RAID opens the drives in exclusive mode, so other
applications cannot use it. In our case, the automatic udev mount happens
faster than processing of the RAID. => libblkid should never identify
partitions of RAID member disks as fule systems.

A simple work-around of these problems would be mounting by path.