Reduce empty directory test coupling to implementation
Reduce empty directory test coupling to implementation

Our previous test required that the implementation use a temporary
directory and unpack the wheel in-place. Now we just provide a
conventional empty directory in the wheel file itself.

pypa/pip,pfmoore/pip,pfmoore/pip,sbidoul/pip,pradyunsg/pip,pypa/pip,sbidoul/pip,pradyunsg/pip