It does happen also in latest Zdoom svn.RazTK from the Skulltag bug forum wrote:You get the opposite effect when you toggle it via the menu. It should be renamed to "Allow Suicide".
[edit]Launch zDoom, open menu, then go to: options -> gameplay options, and you will see that "Disallow suicide" is set as "Yes". Load a new game, then type 'kill' in console. You'll die.
Viceversa, set that option to "no", then retry to kill yourself. You won't die.