If 'only' init param is specified, return early in _update_fields
If 'only' init param is specified, return early in _update_fields

bartaelterman/marshmallow,jmcarp/marshmallow,quxiaolong1504/marshmallow,marshmallow-code/marshmallow,0xDCA/marshmallow,etataurov/marshmallow,xLegoz/marshmallow,Bachmann1234/marshmallow,mwstobo/marshmallow,Tim-Erwin/marshmallow,maximkulkin/marshmallow,VladimirPal/marshmallow,daniloakamine/marshmallow,dwieeb/marshmallow,jmcarp/marshmallow,0xDCA/marshmallow