The Setup files are configuration files, so their handling is different from the handling of Makefile.pre.in or the handling of the source files.

The only reference to Setup.local in the Python documentation is at https://docs.python.org/3/extending/extending.html#compilation-and-linkage, so most users that need to configure the build with a Setup file are probably using Modules/Setup instead of Modules/Setup.local and the solution that implements this enhancement cannot overwrite an existing Modules/Setup file. This solution must also be robust and transparent when switching to/from a branch where the solution is not implemented yet (a bpo branch created earlier).

PR 5062 adds the ``--enable-use-setup-dist`` configure option to use Modules/Setup.dist instead of Modules/Setup to build the Makefile. The build behavior is unchanged when this option is not used.