Improvements for reliable testing with non-default python version
Improvements for reliable testing with non-default python version

jonfoster/pyxb2,pabigot/pyxb,CantemoInternal/pyxb,jonfoster/pyxb-upstream-mirror,jonfoster/pyxb-upstream-mirror,CantemoInternal/pyxb,jonfoster/pyxb2,balanced/PyXB,balanced/PyXB,CantemoInternal/pyxb,jonfoster/pyxb-upstream-mirror,jonfoster/pyxb2,balanced/PyXB,pabigot/pyxb