Fix oops when removing full snapshot
kernel bugzilla bug 7040
If a snapshot became invalid (full) while there is outstanding
pending_exception, pending_complete() forgets to remove
the corresponding exception from its exception table before freeing it.
Already fixed in 2.6.19.
Signed-off-by: Milan Broz <mbroz@redhat.com> Signed-off-by: Chris Wright <chrisw@sous-sol.org>