This reverts most of commit 30e0fca6.
It broke the case of non-leader MT exec when ptraced.
I think the bug it was intended to fix was already addressed by commit
788e05a6.
Signed-off-by: NRoland McGrath <roland@redhat.com>
Acked-by: NOleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>