NoInterpreterInfo confused as missing version

[pytoxbot]

• Bitbucket: https://bitbucket.org/hpk42/tox/issue/165
• Originally reported by: justinabrahms
• Originally created at: 2014-04-12T06:39:19.828

If have PYTHONPATH set, tests for py34 fail with an error indicating that 2.5 is not a supported version.

Had to drop into a debug session to figure this one out. Relevant code snippet below.

 181         def getsupportedinterpreter(self):
 182             import pdb; pdb.set_trace()
 183             if sys.platform == "win32" and self.basepython and \
 184                     "jython" in self.basepython:
 185                 raise tox.exception.UnsupportedInterpreter(
 186                     "Jython/Windows does not support installing scripts")
 187             info = self.config.interpreters.get_info(self.basepython)
 188             if not info.executable:
 189                 raise tox.exception.InterpreterNotFound(self.basepython)
 190             if info.version_info < (2,6):
 191  ->             raise tox.exception.UnsupportedInterpreter(
 192                     "python2.5 is not supported anymore, sorry")
 193             return info.executable
(Pdb++) info
<tox.interpreters.NoInterpreterInfo instance at 0x100ca0f38>
(Pdb++) pp info.__dict__
{'err': 'Failed to import the site module\nYour PYTHONPATH points to a site-packages dir for Python 2.x but you are running Python 3.x!\n     PYTHONPATH is currently: "/usr/local/lib/python2.7/site-packages:"\n     You should `unset PYTHONPATH` to fix this.\n',
 'executable': local('/usr/local/bin/python3.4'),
 'name': 'python3.4',
 'out': '',
 'version_info': None}

[obestwalter]

If the error is still obfuscated like this today that should definitely be fixed. Did not try to reproduce it yet though.

[obestwalter]

PYTHONPATH is explicitly being removed since v2.4.0 so this usage pattern is basically invalid now and the suggestion would be not to use PYTHOPATH (unless we add at as opt in as discussed in #457 atm).

Leaving this open though because I saw confusing error messages around this in other contexts as well, so this needs definitely improving.