Message 368159 - Python tracker

--with-experimental-isolated-subinterpreters option name is very long on purpose: to advertize that you must not use it, unless you fully understand its purpose :-)

I didn't document the build option in Misc/SpecialBuilds.txt or Doc/whatsnew/3.9.rst on purpose: you should not use this special build :-) Basically, this option is only for Eric Snow and me :-D