Fixes a Malf AI exploit, Fixes #5172

Fixes #5172 
HG agreed on doing a var.

17:06	hg|work	RemieRichards: i suggest a variables at the /machinery level
17:06	hg|work	default 1
17:07	RemieRichards	I've done that
17:07	RemieRichards	:)
17:07	RemieRichards	it's compiling now
17:07	hg|work	cool

Why doors, exactly?