cython cleanup: correct name of exception
cython cleanup: correct name of exception

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