travis: keep lint jobs for docs-only changes
travis: keep lint jobs for docs-only changes

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