Process group bug in su command

[Casey Leedom]

| From: philip at cs.vu.nl (Philip Homburg)
| Description:
| 	su should create a new process group for the new shell,
| 	and wait for the new shell to finish in order to reset
| 	the tty process group to its old value.
| 
| Repeat-By:
| 	% sh
| 	$ su somebody-ELSE-with-a-Bourne-shell
| 	Password:
| 	$ csh	# any shell with job control
| 	% exit
| 	% $
| 	Stopped (tty input)	# or Stopped (tty output), depending on
| 	%			# the status of the tostop bit

  This isn't a bug in su.  It's a bug in the shell.