getProcessExitCode doesn't retry on EINTR
Just like the ticket says. The source uses throwErrnoIfMinus1, and I can't think why it shouldn't just use throwErrnoIfMinus1Retry. I think that this is an issue with a few other functions that should do the same thing, including waitForProcess and probably terminateProcess as well.
I also wonder if the same issue is in other core libraries, but that's beyond this ticket.