No it's not. Same problem but on a different part: the two cited issues are about the .pypirc file not the setup.cfg.
The parsing does not occurs at the same place and the fix does not works for setup.cfg (I tried before submitting this issue).

In this specific case, setuptools calls distutils to parse the file so the fix has to be in distutils not setuptools (whereas for .pypirc, this is setuptools which is parsing the file)