I'm not convinced slot_nb_bool is doing the right thing in 
the PyBool_Check(tmp) line.  There used to be a "result = -1;"
right after the PyErr_Format and there isn't anymore (maybe
result gets set to -1 somewhere else but I can't tell where).

Can you undo the refactoring of that function in general?
Some of the decrefs moved around too and they look correct
but it would be easier to tell if they just stayed the same.

Also, did you mean to reindent the long_as_number struct
in longobject.c?