Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2056321
There is a case where a multi-mount tree can be be umounted when it's
still in use.
This MR resolves one (hopefully the only remaining one) of those cases.
Resolves: rhbz#2056321
Signed-off-by: Ian Kent ikent@redhat.com
