Comment 7 for bug 917339

on another ubuntu machine (oneiric server) i get leftover mounts like:
proc on /var/lib/schroot/mount/bootstrap-administrator-1b79165b-24ab-4a6d-8460-4f1ca45927d8/proc type proc (rw)
/dev/pts on /var/lib/schroot/mount/bootstrap-administrator-1b79165b-24ab-4a6d-8460-4f1ca45927d8/dev/pts type none (rw,bind)
proc on /var/lib/schroot/mount/bootstrap-administrator-a9d4e330-6451-41f9-889b-e70ecbcd5cb1/proc type proc (rw)
/dev/pts on /var/lib/schroot/mount/bootstrap-administrator-a9d4e330-6451-41f9-889b-e70ecbcd5cb1/dev/pts type none (rw,bind)

unmounting them gives a warning message

administrator@jenkins-server:~$ sudo umount /var/lib/schroot/mount/bootstrap-administrator-a9d4e330-6451-41f9-889b-e70ecbcd5cb1/dev/pts
[sudo] password for administrator:
umount: /var/lib/schroot/mount/bootstrap-administrator-a9d4e330-6451-41f9-889b-e70ecbcd5cb1/dev/pts: not found

 then the entry is gone from mount