The following forum message was posted by fabioz at http://sourceforge.net/projects/pydev/forums/forum/293649/topic/4543888:
The only way to test without disturbing your current environment would be installing
it in a separate version of eclipse and pointing to a new workspace.
Anyways, just took a quick look and it seems PyDev won't handle your use-case...
Please create a feature request for that expliciting your use case.