[Distutils] Making setuptools play nicer with virtualenv

[Ian Bicking]

Gael Varoquaux wrote:
> I have just out-clevered myself using setuptools and virtualenv:
> 
>  * install foo using "python setup.py develop" (foo being ipython).
> 
>  * download some module bar you want to work on in an isolated environment
> 
>  * create this isolated environment using "virtualenv bar"
> 
>  * in the isolated environment "python setup.py develop" the bar module.
> 
>  * still in the isolated environment, try to import bar in a script
>    installed by foo (aka ipython)
> 
>     --> fails because foo uses the system python, and virtualenv wants
> 	you to use its own python
> 
> One very easy solution to make this work is to have the setuptools
> generated scripts use, under unices, "#!/usr/bin/env python" rather than
> "#!/usr/bin/python". This seems to me like a good solution, in general,
> to follow the user's expectations.
> 
> Is this a change that would be possible?

Sometimes you want to inherit the environment you've activated, but in 
my experience usually this isn't what you'll want.  I find it easier to 
just reinstall any tools (like ipython, nose, etc) that I want to use in 
the virtualenv.

In an ideal situation they could share eggs with the system packages, 
but this only kind of works.  (Sometimes, for reasons I don't always 
understand, easy_install will find and install globally-installed 
packages, creating an executable bound to the virtualenv.)

   Ian