SatelliteQE#808 Ignore mirror_on_sync (SatelliteQE#809)

* Ignore mirror_on_sync

Parameter mirror_on_sync has been added to API
in Katello PR 9834.
This is not returned as part of JSON on entity creation.
Consequently, read() fails.
It could be workarounded by ignoring errors when reading
non-required parameters. Also, this would be fixed if
Satellite started returning that value.
This solves the issue without unnecessary changes
in Nailgun's guts that might break something.

* Update test

nailgun/entities.py

@@ -6259,6 +6259,7 @@ def read(self, entity=None, attrs=None, ignore=None, params=None):
             ignore = set()
         ignore.add('organization')
         ignore.add('upstream_password')
+        ignore.add('mirror_on_sync')
         return super().read(entity, attrs, ignore, params)
 
     def create_missing(self):

tests/test_entities.py

@@ -1278,7 +1278,7 @@ def test_ignore_arg_v1(self):
                 {'discovery', 'remote_execution_proxy', 'subnet_parameters_attributes'},
             ),
             (entities.Subscription, {'organization'}),
-            (entities.Repository, {'organization', 'upstream_password'}),
+            (entities.Repository, {'organization', 'upstream_password', 'mirror_on_sync'}),
             (entities.User, {'password'}),
             (entities.ScapContents, {'scap_file'}),
             (entities.TailoringFile, {'scap_file'}),