Missing mapping.prefix in generated URIs

I'm using resteasy.servlet.mapping.prefix=/rest because my servlet
mapping is /rest/* and when I build a URI using

uriInfo.getBaseUriBuilder().path(Foo.class, "getFoo").build("bar");

with (and from within a call of):

@Path("/")
class Foo {
@Path("/foo/

")
@GET
public Response getFoo(@PathParam key);
}

I get http://localhost/app/foo/bar instead of
http://localhost/app/rest/foo/bar (/rest is missing).

This used to work before (beta1, way old).