The load method, which is also called from the initializer if input is
provided, doesn't create Morsel objects for things other than strs,
because it calls self.update(rawdata), which does not invoke the custom
__setitem__.

The documentation states that when rawdata is not a string, it must be a
dictionary and providing that will be equivalent to doing

for k, v in rawdata.items():
    cookie[k] = v

So that is what it should do :)