vfork / setsid interaction

[Joe Buehler]

One of the problems in the GNU emacs port was an interaction between
setsid() and vfork().

If I understand vfork() correctly, the pid does not change in the
child.  This causes setsid() to fail in the child if the parent is
a process group leader.  This was preventing emacs children from changing
their controlling tty.

I assume this is not "correct" behavior because this is the standard way
that emacs does things on other platforms.

Joe Buehler