Update proof to handle 0 rev charms.

Update proof to handle 0 rev charms.

- When parsing the store url for a rev the regex would return the int 0
- Proof checks to determine if a revision was defined would use if revision
and fail (bool(0) == False)
- Updates the if checks to use if revision is not None, if revision is None
directly.

https://code.launchpad.net/~rharding/charmworld/handle-0-rev/+merge/194526

(do not edit description out of merge proposal)

[rharding, 2013-11-08 14:59:10]

Please take a look.

[rharding, 2013-11-08 15:00:01]

Reviewer comments below.

https://codereview.appspot.com/23600043/diff/1/charmworld/models.py
File charmworld/models.py (right):

https://codereview.appspot.com/23600043/diff/1/charmworld/models.py#newcode1607
charmworld/models.py:1607: if self.revision is not None:
if 0 would fail, so have to check for None directly.

https://codereview.appspot.com/23600043/diff/1/charmworld/views/tests/test_pr...
File charmworld/views/tests/test_proof.py (right):

https://codereview.appspot.com/23600043/diff/1/charmworld/views/tests/test_pr...
charmworld/views/tests/test_proof.py:19: store_revision=0,
to test, just make sure all tests pass with one of the default charms being at
rev 0.

[bac, 2013-11-08 15:05:42]

LGTM, no qa

https://codereview.appspot.com/23600043/diff/1/charmworld/models.py
File charmworld/models.py (right):

https://codereview.appspot.com/23600043/diff/1/charmworld/models.py#newcode1607
charmworld/models.py:1607: if self.revision is not None:
Good change.