fix broken virtualenv without version
fix broken virtualenv without version

graphicore/fontbakery,vitalyvolkov/fontbakery,moyogo/fontbakery,vitalyvolkov/fontbakery,googlefonts/fontbakery,googlefonts/fontbakery,graphicore/fontbakery,moyogo/fontbakery,vitalyvolkov/fontbakery,moyogo/fontbakery,googlefonts/fontbakery,graphicore/fontbakery,davelab6/fontbakery,jessamynsmith/fontbakery