Quickstart crashes when used with juju 1.20

machine 1 provisioning is pending
Traceback (most recent call last):
  File "/usr/bin/juju-quickstart", line 34, in <module>
    manage.run(options)
  File "/usr/lib/python2.7/dist-packages/quickstart/manage.py", line 531, in run
    address = app.watch(env, unit_name)
  File "/usr/lib/python2.7/dist-packages/quickstart/app.py", line 515, in watch
    action, data, machine_status, address)
  File "/usr/lib/python2.7/dist-packages/quickstart/watchers.py", line 122, in parse_machine_change
    public_address = retrieve_public_adddress(addresses)
  File "/usr/lib/python2.7/dist-packages/quickstart/watchers.py", line 82, in retrieve_public_adddress
    scope = address['NetworkScope']
KeyError: u'NetworkScope'

This is related to a recent change in the mega-watcher for machines: see https://github.com/juju/juju/commit/57bad2bed5d3fecda4a1f576b0e6bb77ded2474a

"NetworkScope" is now called just "Scope".