Using Ubuntu 14.04, test fails because 'blkid' < 2.21 doesn't recognize
'ocfs2' filesystem smaller than 108Mo:
6baa150398
filesystem: fix MKFS_FORCE_FLAGS for ocfs2
mkfs.ocfs2 -F won't work because mkfs.ocfs2 asks for a confirmation:
$ mkfs.ocfs2 -F img
mkfs.ocfs2 1.6.4
Cluster stack: classic o2cb
Overwriting existing ocfs2 partition.
WARNING: Cluster check disabled.
Proceed (y/N):
The undocumented 'x' switch must be used too.
