https://bugs.winehq.org/show_bug.cgi?id=45320
--- Comment #7 from Dima Ryazanov dima@gmail.com --- Looks like Python is using _wenviron: https://github.com/python/cpython/blob/master/Modules/posixmodule.c#L1395
I've attached two test files: env.c: prints out the contents of _wenviron test.c: runs env.exe with a custom environment: X=x, Y=y, and =%FOO=bar.
On Wine, I see this:
X=x =%FOO=bar Y=y ProgramW6432=C:\Program Files ProgramFiles=C:\Program Files CommonProgramW6432=C:\Program Files\Common Files CommonProgramFiles=C:\Program Files\Common Files
On Windows 10, I only see:
X=x Y=y
If instead of _wenviron I use GetEnvironmentStrings, then the Wine output stays the same, but on Windows 10, I see:
X=x =%FOO=bar Y=y
So yeah, the =% variables just get filtered out.