addr:housenumber which have all the mkgmap:adminlevel tags
but they don't have the mkgmap:city tag.

It seems that RuleSet.merge() doesn't merge the finalize rules.
I think that's would be an error although I am not sure
how a merge would work.

this problem is solved with r3540. See also
http://www.mkgmap.org.uk/websvn/revision.php?repname=mkgmap&rev=3540

Gerd