BLD: ensure we give the right error message for old Python versions
BLD: ensure we give the right error message for old Python versions

Before this change, it would give a random syntax error somewhere
in `versioneer`.

madphysicist/numpy,anntzer/numpy,jakirkham/numpy,jakirkham/numpy,seberg/numpy,mattip/numpy,pbrod/numpy,endolith/numpy,rgommers/numpy,endolith/numpy,seberg/numpy,mhvk/numpy,simongibbons/numpy,numpy/numpy,jakirkham/numpy,mattip/numpy,pbrod/numpy,madphysicist/numpy,simongibbons/numpy,rgommers/numpy,pbrod/numpy,anntzer/numpy,pdebuyl/numpy,mhvk/numpy,mhvk/numpy,pdebuyl/numpy,madphysicist/numpy,simongibbons/numpy,seberg/numpy,charris/numpy,mattip/numpy,jakirkham/numpy,charris/numpy,jakirkham/numpy,mhvk/numpy,pbrod/numpy,simongibbons/numpy,pbrod/numpy,pdebuyl/numpy,anntzer/numpy,seberg/numpy,numpy/numpy,charris/numpy,charris/numpy,endolith/numpy,pdebuyl/numpy,rgommers/numpy,numpy/numpy,mattip/numpy,simongibbons/numpy,anntzer/numpy,madphysicist/numpy,mhvk/numpy,endolith/numpy,numpy/numpy,rgommers/numpy,madphysicist/numpy