Correct check for namespace uri invocation
Correct check for namespace uri invocation

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