populate_methods() fails, the return status will be -1 (failure)
  instead of 0 (success).

  fini_exceptions(): When decref'ing the static pointers to the
  exception classes, clear out their dictionaries too.  This breaks a
  cycle from class->dict->method->class and allows the classes with
  unbound methods to be reclaimed.  This plugs a large memory leak in a
  common Py_Initialize()/dosomething/Py_Finalize() loop.