configure_model mutates parameter

Currently, configure_model takes a dict as a config and pops the 'yields', it mutates therefore the original argument. I think only a copy of the dictionary should be mutated internally (if needed at all) but not the given parameter from the outer scope.

Do you agree, @apuignav ? Or is this intended (yet unexpected/undocumented) behavior?

I can have a look at the code to search for a possible solution.