Fixed bug that was appear in some versions of python.

- Still not entirely clear on why, as reported by Bill Cauchois,
  but some versions of python were getting errors due to an uninitialized
  local variable. This change corrects it in a way that will work in
  all pythons.

Auditors: benjy
Get rid of pants/ant entirely.

W00t!
Fix bad exception handling in zinc_analysis_cache
Bugfix take two.
Merge pull request #112 from jonboulle/master

zinc_analysis_cache: fix NameError being thrown on IOError
Restore python functionality.

Overzealously deleted in previous commit.
Merge pull request #111 from foursquare/master

Get rid of pants/ant entirely.
Merge branch 'master' into zinc_rebasing