YAMAMOTO Mitsuharu wrote:
> I think resetting the SIGCHLD handler in the vfork child on Darwin is
> still a good thing to do even with the change you installed, if the
> SIGCHLD handler call in such a context is unexpected (and does not
> happen on the other platforms).

Although I'm still not entirely sure we've diagnosed the problem correctly, it 
shouldn't hurt to run that code on macOS, so I installed the attached.