Summary:

Fix ImportError and AttributeError in models.py.

Review Request #5966 — Created June 10, 2014 and submitted June 10, 2014, 12:02 p.m.

Description

Fix ImportError and AttributeError in models.py.

Testing Done

Issues

Description	From	Last Updated
'DiffSet' imported but unused	reviewbot	June 10, 2014, 11:59 a.m.

This is a review from Review Bot.
  Tool: PEP8 Style Checker
  Processed Files:
    extension/reviewbotext/models.py
  Ignored Files:

This is a review from Review Bot.
  Tool: Pyflakes
  Processed Files:
    extension/reviewbotext/models.py
  Ignored Files:

extension/reviewbotext/models.py (Diff revision 1)
Show all issues
```
 'DiffSet' imported but unused
```

-	3bdb2b6ecde195b6c3de185631e0d2ebb3683472
+	ba185d12ffe64068a5fca43792cf865358a4f1d8

This is a review from Review Bot.
  Tool: PEP8 Style Checker
  Processed Files:
    extension/reviewbotext/models.py
  Ignored Files:

This is a review from Review Bot.
  Tool: Pyflakes
  Processed Files:
    extension/reviewbotext/models.py
  Ignored Files:

Ship it!

Pushed to master (13df7b32787d4f24e5586ed3fcb393b22a22ea20).