Fix self-assignment for vector class.
Fix self-assignment for vector class.

SoylentGraham/libmv,Nazg-Gul/libmv,keir/libmv,rgkoo/libmv-blender,petertsoi/libmv,libmv/libmv,SoylentGraham/libmv,libmv/libmv,petertsoi/libmv,SoylentGraham/libmv,libmv/libmv,SoylentGraham/libmv,rgkoo/libmv-blender,Nazg-Gul/libmv,rgkoo/libmv-blender,keir/libmv,rgkoo/libmv-blender,keir/libmv,Nazg-Gul/libmv,keir/libmv,Nazg-Gul/libmv,rgkoo/libmv-blender,Nazg-Gul/libmv,petertsoi/libmv,libmv/libmv,petertsoi/libmv