[OSM-dev] Getting admin_level=* from relations to render properly

[John Smith]

It occurred to me a few weeks ago that ways shouldn't be tagged with
the admin_level, but instead use the information from relations, but
this doesn't work, in fact I removed the admin_level tag from a way
that makes up part of a state border assuming the information would be
used from the relation instead, but it just didn't render at all until
I reinstate the admin_level on the way.

I haven't figured out what needs to be fixed in the mapnik style sheet
to fix this, can anyone tell me what needs tweaking to fix this?