Extract VCS scheme check into helper function
Extract VCS scheme check into helper function

xavfernandez/pip,pfmoore/pip,xavfernandez/pip,pypa/pip,sbidoul/pip,pradyunsg/pip,sbidoul/pip,pypa/pip,rouge8/pip,xavfernandez/pip,pfmoore/pip,pradyunsg/pip,rouge8/pip,rouge8/pip