When running tox, it sets up a virtualenv using the command line:
<python-interpreter> -mvirtualenv --setuptools --python <path-to-py27-bin> py27
This works with CPython, but is not really in line with the documented use of the -m option:
-m mod : run library module as a script (terminates option list)
pyrun uses a different command line parser, since it has to emulate the CPython in Python and does not know how to handle options which use arguments without separating space.
Could this be changed to use "-m virtualenv" instead, to be in line with the Python documentation ?