Fix editing single objects when batchMultiEdit() is enabled (#1479)

Fixes #1475

Author: JonnyWong16

Diff for: plexapi/library.py

@@ -1740,7 +1740,7 @@ def common(self, items):
 
     def _edit(self, items=None, **kwargs):
         """ Actually edit multiple objects. """
-        if isinstance(self._edits, dict):
+        if isinstance(self._edits, dict) and items is None:
             self._edits.update(kwargs)
             return self