[OSM-dev] Osm2pgsql 'route' relations geometry building

[yvecai]

I'm looking for the code in OSm2pgsql responsible for 'route' relations 
pre-processing.

When a relation make a loop on itself (the same way appears twice in the 
relation, backward, then later forward) osm2pgsql does the same: the 
resulting linestring is complete. Certainly great for routing, this has 
some un-desired effects (at least for me) for rendering.
For instance if using 'offset' parameter in mapnik, the forward part 
will be offset left, and the backward right, which I'd like to avoid in 
some cases.
Could somebody points me to the relevant part of the code where I could 
check for duplicate way IDs passed to geos Linemerger ?

Yves, not so good in reading C