Make isolated environments more isolated under OSX and pyvenv. Resolves #217.

pre_commit/main.py

@@ -1,6 +1,7 @@
 from __future__ import unicode_literals
 
 import argparse
+import os
 import sys
 
 import pkg_resources
@@ -15,6 +16,13 @@ from pre_commit.error_handler import error_handler
 from pre_commit.runner import Runner
 
 
+# https://github.com/pre-commit/pre-commit/issues/217
+# On OSX, making a virtualenv using pyvenv at . causes `virtualenv` and `pip`
+# to install packages to the wrong place.  We don't want anything to deal with
+# pyvenv
+os.environ.pop('__PYVENV_LAUNCHER__', None)
+
+
 def main(argv=None):
     argv = argv if argv is not None else sys.argv[1:]
     parser = argparse.ArgumentParser()