[mkup]

Copy-on-write fork is not compatible with Win32 global (interprocess) mutexes. After fork succeeds in context of process with acquired global mutex, should parent or child automatically release that mutex?

Copy-on-write fork existed in POSIX subsystem of Windows NT (MS Services for UNIX aka Interix), hence no global mutexes in that subsystem.

There are global mutexes in Win32 subsystem of Windows NT, hence no fork.

And on "true" POSIX systems with pthreads there are mutexes and fork, but mutexes are process-local (kind of Win32 critical sections).