Rack controller REJECTED by the region (rackd dead)

[Kit Randel]

Having installed the maas snap from edge (2.7.0-8101-g.b3b43022d r4577), after some time rackd dies and becomes unavailable. Restarting maas with `sudo snap restart maas` does not fix the issue.

As far as I'm aware, the only steps I've taken since installation were:

1. Download an 18.04/amd64 image
2. Upload a 'fake' windows image via the cli
3. Add a license key for the windows image

All images now sit in the "Waiting for rack controller(s) to sync" state.

Please see the attached log for the relevant traceback.

Our CI also fails in test_region_rack_connected(), which might be the
same issue:
  http://10.245.136.4:8080/job/maas-bionic-master-git/913/console

[Björn Tillenius (bjornt)]

I added a link to our failed CI run in the description, since that is most likely the same issue:

  http://10.245.136.4:8080/job/maas-bionic-master-git/913/console