vmalloc/mongomock — pull request #70 by toddtomkinson (2013-10-28 17:16:35+00:00)
Title: fixing "global name DuplicateKeyError is not defined" error

I was running some tests and ran into the following error:

```
File ".../mongomock/mongomock/collection.py", line 59, in _insert
raise DuplicateKeyError("Duplicate Key Error", 11000)
NameError: global name 'DuplicateKeyError' is not defined
```

This fixes it.