Confusing setuptools behaviour with virtualenv-burrito in the PYTHONPATH

[brainsik]

The PYTHONPATH environment variable includes the virtualenv-burrito site-packages. This causes bad behaviour for setuptools as the version in there will override whatever is actually installed in the virtualenv itself.

The site-packages is included in order to make virtualenvwrapper function.

[silentninja]

+1 Moreover pip freeze includes virtualenv-burrito packages

[brainsik]

As a partial work-around, I'm currently matching the version of setuptools installed by virtualenv-burrito to the version installed by virtualenv. This means virtualenvs will have consistent setuptools versions, which should remove some (most?) of the confusing cases.

Leaving this open for a full fix.