Fix unit tests

Author: cderici

juju/model.py

@@ -1655,12 +1655,8 @@ async def debug_log(
 
     def _get_series(self, entity_url, entity):
         # try to get the series from the provided charm URL
-        if entity_url.startswith('cs:'):
-            parts = entity_url[3:].split('/')
-        else:
-            parts = entity_url.split('/')
-        if parts[0].startswith('~'):
-            parts.pop(0)
+        parts = entity_url.split('/')
+
         if len(parts) > 1:
             # series was specified in the URL
             return parts[0]

tests/unit/test_model.py

@@ -118,10 +118,7 @@ def test_get_series():
             },
         },
     }
-    assert model._get_series('ch:trusty/ubuntu', entity) == 'trusty'
     assert model._get_series('xenial/ubuntu', entity) == 'xenial'
-    assert model._get_series('~foo/xenial/ubuntu', entity) == 'xenial'
-    assert model._get_series('~foo/ubuntu', entity) == 'xenial'
     assert model._get_series('ubuntu', entity) == 'xenial'
     assert model._get_series('ch:ubuntu', entity) == 'xenial'