The merge request has a regression:

Application Malfunction Detected                        
                                                                                
Traceback (most recent call last):                                              
  File "/usr/lib/python3/dist-packages/guacamole/core.py", line 248, in eat     
    return self._dispatch()                                                     
  File "/usr/lib/python3/dist-packages/guacamole/core.py", line 298, in _dispatch
    result = ingredient.dispatch(self.context)                                  
  File "/usr/lib/python3/dist-packages/guacamole/ingredients/cmdtree.py", line 152, in dispatch
    return self._dispatch(context, 0)                                           
  File "/usr/lib/python3/dist-packages/guacamole/ingredients/cmdtree.py", line 179, in _dispatch
    return self._dispatch_None(context, level, retval, command)                 
  File "/usr/lib/python3/dist-packages/guacamole/ingredients/cmdtree.py", line 208, in _dispatch_None
    return self._dispatch(context, level + 1)                                   
  File "/usr/lib/python3/dist-packages/guacamole/ingredients/cmdtree.py", line 165, in _dispatch
    retval = command.invoked(context)                                           
  File "/usr/lib/python3/dist-packages/checkbox_ng/launcher/master.py", line 141, in invoked
    self.connect_and_run(ctx.args.host, port)                                   
  File "/usr/lib/python3/dist-packages/checkbox_ng/launcher/master.py", line 198, in connect_and_run
    }[state]()                                                                  
  File "/usr/lib/python3/dist-packages/checkbox_ng/launcher/master.py", line 221, in new_session
    tps = self.sa.start_session(configuration)                                  
  File "/usr/lib/python3/dist-packages/plainbox/vendor/rpyc/core/netref.py", line 199, in __call__
    return syncreq(_self, consts.HANDLE_CALL, args, kwargs)                     
  File "/usr/lib/python3/dist-packages/plainbox/vendor/rpyc/core/netref.py", line 75, in syncreq
    return conn.sync_request(handler, proxy, *args)                             
  File "/usr/lib/python3/dist-packages/plainbox/vendor/rpyc/core/protocol.py", line 471, in sync_request
    return self.async_request(handler, *args, timeout=timeout).value            
  File "/usr/lib/python3/dist-packages/plainbox/vendor/rpyc/core/async_.py", line 97, in value
    raise self._obj                                                             
plainbox.vendor.rpyc.core.vinegar/psutil._exceptions._get_exception_class.<locals>.Derived: None
                                                                                
========= Remote Traceback (1) =========                                        
Traceback (most recent call last):                                              
  File "/usr/lib/python3/dist-packages/psutil/_pslinux.py", line 1390, in wrapper
    return fun(self, *args, **kwargs)                                           
  File "/usr/lib/python3/dist-packages/psutil/_pslinux.py", line 1512, in environ
    with open_text("%s/%s/environ" % (self._procfs_path, self.pid)) as f:       
  File "/usr/lib/python3/dist-packages/psutil/_pslinux.py", line 201, in open_text
    return open(fname, "rt", **kwargs)                                          
PermissionError: [Errno 13] Permission denied: '/proc/1/environ'                
                                                                                
During handling of the above exception, another exception occurred:             
                                                                                
Traceback (most recent call last):                                              
  File "/usr/lib/python3/dist-packages/plainbox/vendor/rpyc/core/protocol.py", line 329, in _dispatch_request
    res = self._HANDLERS[handler](self, *args)                                  
  File "/usr/lib/python3/dist-packages/plainbox/vendor/rpyc/core/protocol.py", line 590, in _handle_call
    return obj(*args, **dict(kwargs))                                           
  File "/usr/lib/python3/dist-packages/plainbox/impl/session/remote_assistant.py", line 168, in fun
    return f(self, *args)                                                       
  File "/usr/lib/python3/dist-packages/plainbox/impl/session/remote_assistant.py", line 222, in start_session
    'extra_env': self.prepare_extra_env(),                                      
  File "/usr/lib/python3/dist-packages/plainbox/impl/session/remote_assistant.py", line 193, in prepare_extra_env
    p_environ = psutil.Process(p).environ()                                     
  File "/usr/lib/python3/dist-packages/psutil/__init__.py", line 837, in environ
    return self._proc.environ()                                                 
  File "/usr/lib/python3/dist-packages/psutil/_pslinux.py", line 1393, in wrapper
    raise AccessDenied(self.pid, self._name)                                    
psutil._exceptions.AccessDenied: psutil.AccessDenied (pid=1)                    
                                                                                
                                                                                
                                                                                
  Please report a bug including the information from the paragraph above. To    
  report the bug visit https://bugs.launchpad.net/checkbox-ng/+filebug          
                                                                                
  We are sorry for the inconvenience!