Currently, -X tracemalloc=0 command line option is reject as an invalid value. I would like to allow to explicitly disable tracemalloc. That's useful to ignore the PYTHONTRACEMALLOC environment variable: "PYTHONTRACEMALLOC=1 python3 -X tracemalloc=0" would not enable tracemalloc at startup.
I don't think that it's worth it to backport this change. It's really a corner case and it's almsot a bugfix. I mostly need it for testing _PyCoreConfig and Python initialisation.