Since bpo-36302 was implemented, extension sources are now sorted for reproducibility. This is causing an issue in pywin32 as the *.mc files must be processed first to ensure the *.h files are generated before trying to compile the actual sources. I'm not very familiar with Windows but there are more details in: https://github.com/mhammond/pywin32/issues/1590

As suggested in the issue, the solution is probably to modify msvccompiler.py to process the .rc and .mc files before any C/C++ sources.