I managed to get a commissioning node to get past enlistment so I could commission with the `allow ssh` option.

I noted a couple of interesting errors from cloud-init logs:

```
2019-11-05 20:51:47,862 - util.py[DEBUG]: Running command ['/var/lib/cloud/instance/scripts/runcmd'] with allowed return codes [0] (shell=False, capture=False)                                     
2019-11-05 20:51:47,870 - util.py[WARNING]: Failed running /var/lib/cloud/instance/scripts/runcmd [127]                                                                                             
2019-11-05 20:51:47,870 - util.py[DEBUG]: Failed running /var/lib/cloud/instance/scripts/runcmd [127]                                                                                               
Traceback (most recent call last):                                                                                                                                                                  
  File "/usr/lib/python3/dist-packages/cloudinit/util.py", line 870, in runparts                                                                                                                    
    subp(prefix + [exe_path], capture=False)                                                                                                                                                        
  File "/usr/lib/python3/dist-packages/cloudinit/util.py", line 2065, in subp                                                                                                                       
    cmd=args)                                                                                                                                                                                       
cloudinit.util.ProcessExecutionError: Unexpected error while running command.                                                                                                                       
Command: ['/var/lib/cloud/instance/scripts/runcmd']                                                                                                                                                 
Exit code: 127                                                                                                                                                                                      
Reason: -                                                                                                                                                                                           
Stdout: -                                                                                                                                                                                           
Stderr: -                                                                                                                                                                                           
2019-11-05 20:51:47,877 - util.py[DEBUG]: Running command ['/var/lib/cloud/instance/scripts/user_data.sh'] with allowed return codes [0] (shell=False, capture=False)                               
2019-11-05 20:52:59,003 - cc_scripts_user.py[WARNING]: Failed to run module scripts-user (scripts in /var/lib/cloud/instance/scripts)                                                               
2019-11-05 20:52:59,005 - url_helper.py[DEBUG]: [0/1] open 'http://192-168-2-0--24.maas-internal:5248/MAAS/metadata/status/qdpd87' with {'method': 'POST', 'headers': {'Authorization': 'OAuth oauth
_nonce="123063311710824411781572987179", oauth_timestamp="1572987179", oauth_version="1.0", oauth_signature_method="PLAINTEXT", oauth_consumer_key="J4r8FcjhaGmPTkjqwY", oauth_token="FVWwc3fXZDaUSu
aPWe", oauth_signature="%26uvQtSWmCthUyFYdUaKTkW4DcNwXnQTuY"'}, 'allow_redirects': True, 'url': 'http://192-168-2-0--24.maas-internal:5248/MAAS/metadata/status/qdpd87'} configuration              
2019-11-05 20:52:59,014 - url_helper.py[DEBUG]: Read from http://192-168-2-0--24.maas-internal:5248/MAAS/metadata/status/qdpd87 (204, 0b) after 1 attempts                                          
2019-11-05 20:52:59,015 - handlers.py[DEBUG]: finish: modules-final/config-scripts-user: FAIL: running config-scripts-user with frequency once-per-instance                                         
2019-11-05 20:52:59,015 - util.py[WARNING]: Running module scripts-user (<module 'cloudinit.config.cc_scripts_user' from '/usr/lib/python3/dist-packages/cloudinit/config/cc_scripts_user.py'>) fail
ed                                                                                                                                                                                                  
2019-11-05 20:52:59,015 - util.py[DEBUG]: Running module scripts-user (<module 'cloudinit.config.cc_scripts_user' from '/usr/lib/python3/dist-packages/cloudinit/config/cc_scripts_user.py'>) failed
Traceback (most recent call last):                                                                                                                                                                  
  File "/usr/lib/python3/dist-packages/cloudinit/stages.py", line 812, in _run_modules                                                                                                              
    freq=freq)                                                                                                                                                                                      
  File "/usr/lib/python3/dist-packages/cloudinit/cloud.py", line 54, in run                                                                                                                         
    return self._runners.run(name, functor, args, freq, clear_on_fail)                                                                                                                              
  File "/usr/lib/python3/dist-packages/cloudinit/helpers.py", line 188, in run
    return (True, results)
  File "/usr/lib/python3.5/contextlib.py", line 77, in __exit__
    self.gen.throw(type, value, traceback)
  File "/usr/lib/python3/dist-packages/cloudinit/helpers.py", line 76, in lock
    yield self._acquire(name, freq)
  File "/usr/lib/python3/dist-packages/cloudinit/helpers.py", line 187, in run
    results = functor(*args)
  File "/usr/lib/python3/dist-packages/cloudinit/config/cc_scripts_user.py", line 45, in handle
    util.runparts(runparts_path)
  File "/usr/lib/python3/dist-packages/cloudinit/util.py", line 877, in runparts
    % (len(failed), len(attempted)))
RuntimeError: Runparts: 1 failures in 2 attempted commands
2019-11-05 20:52:59,039 - stages.py[DEBUG]: Running module ssh-authkey-fingerprints (<module 'cloudinit.config.cc_ssh_authkey_fingerprints' from '/usr/lib/python3/dist-packages/cloudinit/config/cc_ssh_authkey_fingerprints.py'>) with frequency once-per-instance
```

I'll try and post full logs to this bug report...