mount: mtab created multiple times with -a option

mount: mtab created multiple times with -a option

When /etc/mtab does not exist and mount is called with -a, for every
mount point that is mounted a root-fs record is added to mtab. This is
because get_mtab_info() sets the flag mtab_does_not_exist to 1 when it
doesn't find /etc/mtab. However, if it actually finds /etc/mtab, the
variable is not reset to 0. So on every subsequent call to
get_mtab_info() (as it is the case when mounting several mount points
with the -a option), mount will think that /etc/mtab does not exist,
even if it was created in the meantime by mount itself.

Reported-By: Jonas Kramer <jkramer@nex.scrapping.cc>
Signed-off-by: Karel Zak <kzak@redhat.com>