[patch] sshd with re-exec disabled causes stdin to get closed.

[Dave Johnson]

I ran into a bug while testing 3.9p1.

If you start sshd with -r (re-exec disabled), once the daemon is
forked to handle a client, the child closes stdin by accident.

This causes FD 0 to get re-used by the next open call which eventually
you end up with a mess.  In the perticual case I saw, the pty fd
ended up on FD 0 was closed by do_exec_pty(),
pty_make_controlling_tty() then opened a new ttyfd as 0, and
do_exec_pty() duped it dup2(0,0), dup2(0,1), dup2(0,2), then called
close(ttyfd); which closed 0!

Patch against openssh-3.9p1 is attached.

-- 
Dave