Fixed django test class
Fixed django test class

refs hmarr/mongoengine#506

sourcelair/mongoengine,muhammad-ammar/mongoengine,RussellLuo/mongoengine,iandd0824/mongoengine,MakerReduxCorp/mongoengine,prijindal/mongoengine,noirbizarre/mongoengine,losintikfos/mongoengine,MongoEngine/mongoengine,ms5/mongoengine,Multiposting/mongoengine,MRigal/mongoengine,ConsumerPhysics/mongoengine,yarneo/mongoengine,nathanial/mongoengine,ProgressivePlanning/mongoengine,cogniteev/mongoengine,elephanter/mongoengine,MakerReduxCorp/mongoengine,Davidrjx/mongoengine,closeio/mongoengine,jimmyshen/mongoengine,nicolascine/mongoengine,reallistic/mongoengine,khallaghi/mongoengine,depop/mongoengine-stripped,WingGao/mongoengine,DavidBord/mongoengine,larsbutler/mongoengine,cogniteev/mongoengine,gavincabbage/mongoengine,blaggacao/mongoengine,9nix00/mongoengine,starsirius/mongoengine,Catstyle/mongoengine,gmacon/mongoengine,touilleMan/mongoengine,Davidrjx/mongoengine,hmarr/mongoengine,eli-b/mongoengine