Do not unconditionally mount devfs to ${jail_devdir}/dev. First check to see if a prior devfs has been mounted. If no devfs is mounted on ${jail_devdir}/dev then proceed. This will prevent the stack up of multiple devfs mounts on the same mount point.
Do not unconditionally mount devfs to ${jail_devdir}/dev. First check
to see if a prior devfs has been mounted. If no devfs is mounted on
${jail_devdir}/dev then proceed. This will prevent the stack up of
multiple devfs mounts on the same mount point.

Discussed with:	pjd
MFC after:	1 week

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