handle unknown routers
handle unknown routers

it can happen that tor extends circuits to routers which don't exist in the
consensus (i.e. in getinfo ns/all) so we have to handle those cases.

meejah/txtorcon,meejah/txtorcon,david415/txtorcon,ghtdak/txtorcon,isislovecruft/txtorcon,david415/txtorcon,sammyshj/txtorcon,sammyshj/txtorcon,ghtdak/txtorcon,isislovecruft/txtorcon