Description
the -extra-search-dir feature as described in the docs to support alternative versions, only works for pip (and even it's support for pip is pretty limited; see below)
I don't see that it could have ever worked as described.
for distribute and setuptools, alternative archives can be found in an alternative directory, but only if they are the default version, which defeats the point of the feature.
for pip, alternative versions of pip can be found, but only if there is no greater version of pip, in the search dir path.
Details for distribute:
supposing you have an alternative source dist of distribute in an extra dir (i.e. not the DEFAULT_VERSION specified in the embedded distribute_setup.py), virtualenv will find that version, but distribute_setup.py (as a called script) is only capable of installing the DEFAULT_VERSION. See the download_setuptools method in distribute_setup.py and follow the code leading up to it. Btw, any cli arguments passed to distribute_setup.py are used as install arguments to the python setup.py install call for distribute.
Details for setuptools:
Supposing you have an alternative version of setuptools in an extra dir (i.e. not the DEFAULT_VERSION specified in the embedded ez_setup.py), virtualenv will find the egg, and pass it as an argument to ez_setup.py (and add it to the PYTHONPATH). Due to the internals of ez_setup.py, what happens is the found version gets installed, then uninstalled, and then the DEFAULT_VERSION get's installed.