In the case of instance methods for updates, pass in the class vs. the object
In the case of instance methods for updates, pass in the class vs. the object

Summary:
In the asynchronouse case, we pickle the (self) object in instance methods, but sometimes those objects aren't picklable

The __class__ should always be however

Test Plan: ran locally

Reviewers: bpalsson, tjackson, rli, david, shaw

Differential Revision: https://phab.wish.com/D49248

ContextLogic/mongoengine,ContextLogic/mongoengine