Fix the issue of using a REALLY old controller

Using an older controller that doesn't have the facade available causes
all sorts of issues, this cleans up the issues around that.

Author: SimonRichardson

examples/deploy_bundle.py

@@ -15,7 +15,7 @@ async def main():
     # connect to current controller with current user, per Juju CLI
     await controller.connect()
 
-    bundles = [('juju-qa-bundle-test', None), ('cs:~juju-qa/bundle/basic-0', 'beta')]
+    bundles = [('cs:~juju-qa/bundle/basic-0', 'beta'), ('juju-qa-bundle-test', None)]
     for i in range(len(bundles)): 
         deployment = bundles[i]
         model = await controller.add_model('model{}'.format(i))

juju/bundle.py

@@ -420,21 +420,22 @@ def __init__(self, change_id, requires, params=None):
             self.options = params[3]
             self.constraints = params[4]
             self.storage = {k: parse_storage_constraint(v) for k, v in params[5].items()}
+            self.channel = None
             if len(params) == 8:
                 # Juju 2.4 and below only sends the endpoint bindings and resources
                 self.endpoint_bindings = params[6]
                 self.resources = params[7]
                 self.devices = None
                 self.num_units = None
-                self.channel = None
             else:
                 # Juju 2.5+ sends devices before endpoint bindings, as well as num_units
                 # There might be placement but we need to ignore that.
                 self.devices = {k: parse_device_constraint(v) for k, v in params[6].items()}
                 self.endpoint_bindings = params[7]
                 self.resources = params[8]
                 self.num_units = params[9]
-                self.channel = params[10]
+                if len(params) > 10:
+                    self.channel = params[10]
 
         elif isinstance(params, dict):
             AddApplicationChange.from_dict(self, params)

juju/model.py

@@ -1564,7 +1564,7 @@ async def _add_charm(self, charm_url, origin):
             return await charms_facade.AddCharm(charm_origin=origin, url=charm_url, force=False)
 
         client_facade = client.ClientFacade.from_connection(self.connection())
-        await client_facade.AddCharm(channel=origin.channel, url=charm_url, force=False)
+        await client_facade.AddCharm(channel=str(origin.risk), url=charm_url, force=False)
 
     async def _resolve_charm(self, url, origin):
         charms_cls = client.CharmsFacade