2to3: exclude 2to3 from scripts to be mutated
2to3: exclude 2to3 from scripts to be mutated

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