When building from source, if I create multiple configuration directories and build from there e.g.:

mkdir configs
cd configs
mkdir config-A
cd config-A
../../configure
make
cd ..
mkdir config-B
cd config-B
../../configure --enable-shared
make
cd ../config-A
./python -c "import sysconfig; print(sysconfig.get_config_var('CONFIG_ARGS')

then sysconfig's settings are the same for *every* config, reflecting those of the last build (config-B above, rathern than those of config-A).

This turns out to be due to this:
   ./python -SE -m sysconfig --generate-posix-vars
This generates $(srcdir)/Lib/_sysconfigdata.py for whichever config was last

Is there a way of fixing this whilst keeping it a python file?  Or do we need to build from a C file, perhaps?