Fix for:Base document _mark_as_changed bug #1369
Fix for:Base document _mark_as_changed bug #1369

Davidrjx/mongoengine,Davidrjx/mongoengine,MongoEngine/mongoengine,cogniteev/mongoengine,ConsumerPhysics/mongoengine,MakerReduxCorp/mongoengine,MakerReduxCorp/mongoengine,cogniteev/mongoengine