login shell doesn't send SIGHUP to background jobs when it receives a SIGHUP

[krader1961]

I took some time to write tests to resolve #1359 and was surprised that one of them fails on every platform. After some debugging it occurred to me to verify whether ksh actually behaves as documented. The answer is, it doesn't. This is from ksh93u+ but the current version behaves the same:

20:45 macpro ~/p/3/a/build (disown-tests)> /bin/ksh -l
KSH PROMPT:1: echo $$
64845
KSH PROMPT:2: /bin/sleep 33 &
[1]     64852
KSH PROMPT:3:
fish: '/bin/ksh -l' terminated by signal SIGHUP (Terminal hung up)
20:45 macpro ~/p/3/a/build (disown-tests)> ps -fp 64852
  UID   PID  PPID   C STIME   TTY           TIME CMD
  501 64852     1   0  8:45PM ttys011    0:00.00 /bin/sleep 33

Bash behaves as expected:

20:46 macpro ~/p/3/a/build (disown-tests)> bash -l
macpro:build krader$ echo $$
64883
macpro:build krader$ /bin/sleep 33 &
[1] 64895
macpro:build krader$ fish: 'bash -l' terminated by signal SIGHUP (Terminal hung up)
20:47 macpro ~/p/3/a/build (disown-tests)> ps -fp 64895
  UID   PID  PPID   C STIME   TTY           TIME CMD

The current ksh behavior means that disown isn't needed.