> Traditionally, MingW-compiled Python binaries would often be
binary-incompatible

I don't plan to distribute a MinGW compiled package as an alternative to the official MSVC based build. In my particular use case, I compile everything into a single exe and put the Lib/*.py files into a single zip file. The result is a two-file Python distribution which doesn't need an installation. If somebody is interested, I can elaborate, but this would be off-topic here.

As for the reproducibility issue: The configure/Makefile system coming with Python simply doesn't support creating a Windows build. I hope it's clear that the patch is NOT about creating a Windows installer. If this is a requirement for getting my patch in, please let me know so I can stop wasting my time!

Whatsoever, if you simply want to reproduce that my compile (!) fixes work, please follow these steps:
- Start a MinGW shell and cd into the Python source tree
- CFLAGS="-IPC -IPython" ./configure
- Remove the created pyconfig.h and replace PC/pyconfig.h with the manually modified version I'm attaching
- Modify the Makefile:
-- Remove pwdmodule.c from the MODOBJS variable
-- Add to the MODOBJS variable: PC/dl_nt.o PC/import_nt.o
-- Remove the LIBOBJS variable assigment
-- Edit the "# Build the interpreter" paragraph: Add PC/empty.o to the rule dependencies *AND* after "...$(SYSLIBS) $(LDLAST)"
- Modify PC/empty.c: Add "#include "Python.h" as first line; replace 'return 0;' by 'wchar_t *wargv[] = { L"python.exe", NULL }; return Py_Main(1, wargv);'
- Run make
- Add the the full path to the Lib directory to your PYTHONPATH