Bug#788062: os-prober corrupts LVs/partitions while being mounted inside a VM

[Andrey Korolyov]

The same behavior was observed for ext4 - if *any* superblock update
was made during os-prober execution, it could effectively corrupt a
filesystem in guest or, as for iSCSI, an exported one. The right
solution is to make a filesystem-specific checks like checking
EXT2_MF_BUSY before making an actual probe. Dirty and ugly patch may
land soon and I expect this issue to be re-routed to the upstream.