Add information to the assertion failure
Add information to the assertion failure

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