Support PEP 405
I'm experimenting with the PEP 405 virtual environment support in Python 3.3. It would be nice if pylauncher could detect an active virtual environment when searching for Python 3.3+ (e.g. look in %VIRTUAL_ENV%\Scripts if _OLD_VIRTUAL_PATH is defined).
I can add a custom command to my %localappdata%\py.ini, such as "vpython=python.exe", which works since pylauncher searches the PATH. But it would be simpler if this worked out of the box with a generic shebang such as "#!/usr/bin/python3".
Edit: I didn't check the complete list of issues beforehand. This is a duplicate of issue 15. After experimenting further to install packages with easy_install, I found out that it modifies the shebang for installed scripts. I didn't expect that on Windows.