+ // The only two remaining errors are ECHILD (other code reaped the
+ // child?), or EINVAL (cosmic rays?), and both merit an abort:
+ PCHECK(found != -1) << "waitpid(" << pid_ << ", &status, WNOHANG)";
+ // Though the child process had quit, this call does not close the pipes
+ // since its descendants may still be using them.