Python 2.5-2.6 compatibility fix
Python 2.5-2.6 compatibility fix

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