Detect use of unrecognized namespace (poorly)
Detect use of unrecognized namespace (poorly)

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