This is discussed on https://github.com/pypa/virtualenv/issues/88

I noticed that the original Sage bug report requested that no-user-cfg be supported in the global distutils config file; this is more acceptable than adding an environment variable.  I’m not sure it would solve your problem though, which looks more educational than technical (i.e. people may forget to use an option on the command line or in the config file, so adding support for an option in the config file may not help).  Do you think it would be a useful feature anyway?

Anyway, don’t forget that distutils is closed to feature requests, and this would only land in distutils2 (included in Python 3.3 and released on PyPI for older versions), so I suspect a fix here would take years to be of benefit to your community.  I’m sorry about this situation, and I do hope a fix in virtualenv (which has a faster release cycle and don’t require you to change code in the distributed projects) will solve your problem in a near future.