pypa/virtualenv — pull request #374 by ptone (2012-12-08 06:11:26+00:00)
Title: Fixed the name for the pypy include lib

As noted here: http://doc.pypy.org/en/latest/getting-started-python.html#installation

pypy will look for a lib_pypy directory, and if not found, will use its compiled in sys.path

a consequence of this is that sys.prefix will not be set

virtualenv will then bail out as it expects this to be set here:

https://github.com/pypa/virtualenv/blob/develop/virtualenv.py#L1516

this relatively small change seems to set things straight