Interwiki links to pages with underscore in link don't work

[jhsoby]

I tried linking [[openstreetmap:Relation:route_master]], but it didn't work. [[openstreetmap:Main Page]] works, so there's something going on with the colon in the title.

[jhsoby]

Update: It's not the colon that causes problems, it's the underscore! [[openstreetmap:Relation:route master]] works.