Create virtualenvs from alternate virtualenv versions
I want to create virtualenvs from non-system virtualenv source code, for example because the system-installed package is out-of-date. Please add an option to use an alternate version of virtualenv when creating an environment.
At the moment I use this method http://stackoverflow.com/questions/6812207/how-can-i-correctly-install-multiple-non-package-distribute-virtualenv-pip-ecosys/6875127#6875127 which is based on this method http://stackoverflow.com/questions/4324558/whats-the-proper-way-to-install-pip-virtualenv-and-distribute-for-python/5177027#5177027
Hopefully that gives you an idea of what I'm trying to achieve (and how it may relate to https://bitbucket.org/dhellmann/virtualenvwrapper/issue/105/create-virtualenvs-from-multiple-pythons ). My impression is that this is a core change rather than something that can be done with an extension, if I'm wrong please point me in the right direction!