I'm confused (probably because I'm thinking like make): when a file depends on one that doesn't exist, it's not properly up-to-date (c.f. the ok3 test, albeit we know there how to recreate the missing file).  When we have no way to recreate the missing file, there is indeed some sense in not trying to fix the thing that depends on it; but it still feels like a "promise not kept" situation - the target isn't up-to-date unless generated from its sources, which must all exist.  The admin probably needs to create the file that was taken for granted (hence no rule to make it), for which they'll need *something* to say there's a problem.