snap package revision unable to uninstall

[Brad Marshall]

I have a situation where I am unable to uninstall a revision of a snap, when I run the command:

  $ sudo snap remove prometheus-openstack-exporter --revision=14
  2017-10-25T03:19:28Z ERROR cannot remove snap file "prometheus-openstack-exporter", will retry in 3 mins: umount: /snap/prometheus-openstack-exporter/14: not mounted

It then keeps retrying to remove the snap, and never makes any progress. This is also occuring for the core snap. This is breaking any auto upgrades of snaps on this system.

This is occuring on Xenial LXCs on a variety of snap package versions, including the latest.

Please let me know if you need any more information.

$ lsb_release -rd
Description: Ubuntu 16.04.3 LTS
Release: 16.04

$ dpkg-query -W snapd
snapd 2.27.5

[Michael Vogt (mvo)]

I tried to reproduce by manually unmount a snap revision and remove it then. When I manually umount `snap list --all` will break (as expected) however `snap remove snap --revision=X` works. Any hints how I can reproduce this?