test.
POSIX says that SIGPIPE affects a process and therefore a SIGPIPE caused and
received by a subshell environment may or may not affect the parent shell
environment.
The change assumes that ${SH} is executed in a new process. This must be the
case if it contains a slash and everyone appears to do so anyway even though
POSIX might permit otherwise.
This change makes builtins/wait3.0 work in ksh93.
ccb8c35eab