On commit 1a902a96 we removed this helper to make use of polymorphic
routes but when it's called for Legislation::Proposal fails as the
namespace does not match the model namespace.
Now we recover the removed helper but only the parts that do not work
with polymorphic_url helper.
Co-Authored-By: Javi Martín <javim@elretirao.net>
450b157a5e