[Distutils] The future of invoking pip

[Vincent Povirk]

> Typically, people using "pip" to install stuff, and finding it gets
> installed into the "wrong" Python installation (i.e., not the one they
> expected). I'm not clear myself on how this happens, but it seems to
> be common on some Linux distros (and I think on OSX as well) where
> system and user-installed Pythons get confused.

FWIW, the approach I'm taking for the oneget provider is that, if
there's more than one version of python into which you "can" install a
package (the definition of "can install" is a bit hairy, but for right
now it means the versions with wheels if there are any wheels), it'll
print a message listing the installs you can use. You can then specify
an install using -PythonVersion 3.4 or -PythonLocation
c:\python34\python.exe.

The -PythonVersion switch implicitly uses a wildcard compare (3.4.*)
even though the wildcard is not specified.