PYTHON-981 - Optimize looking for $out in aggregation pipeline.
PYTHON-981 - Optimize looking for $out in aggregation pipeline.

mongodb/mongo-python-driver,ShaneHarvey/mongo-python-driver,aherlihy/mongo-python-driver,aherlihy/mongo-python-driver,ShaneHarvey/mongo-python-driver,ramnes/mongo-python-driver,ShaneHarvey/mongo-python-driver,mongodb/mongo-python-driver,aherlihy/mongo-python-driver,mongodb/mongo-python-driver,ramnes/mongo-python-driver,ramnes/mongo-python-driver