Correct reference for xs prefix
Correct reference for xs prefix

jonfoster/pyxb1,balanced/PyXB,jonfoster/pyxb2,jonfoster/pyxb-upstream-mirror,jonfoster/pyxb-upstream-mirror,jonfoster/pyxb-upstream-mirror,jonfoster/pyxb2,pabigot/pyxb,CantemoInternal/pyxb,balanced/PyXB,CantemoInternal/pyxb,jonfoster/pyxb1,CantemoInternal/pyxb,balanced/PyXB,jonfoster/pyxb2,pabigot/pyxb