I'll note that in ZC 1.5.7, that entire "process" has been removed from the core files. Implementation would use an observer to capture related data if it is/was necessary for diagnostics. A possible scenario here is that a 1.5.7 database was applied to a 1.5.6 set of software... or as I have occasionally seen, the configuration didn't appear to be something desired to use/access so it was just removed from the database. That way it couldn't be abused even though the software wasn't prepared for its complete absence of being set...