add_route_timestamps: do not re-request trip id if it is already known

			my $route    = $in_transit->{route};

			my $train_id = $train->train_id;

			# TODO get_tripid_p is only needed on the first call, afterwards the tripid is known.

			$self->hafas->get_tripid_p( train => $train )->then(

			my $tripid_promise;

			if ( $in_transit->{data}{trip_id} ) {

				$tripid_promise

				  = Mojo::Promise->resolve( $in_transit->{data}{trip_id} );

			}

			else {

				$tripid_promise = $self->hafas->get_tripid_p( train => $train );

			}

			$tripid_promise->then(

				sub {

					my ($trip_id) = @_;

					if ( not $in_transit->{extra_data}{trip_id} ) {

						$self->in_transit->update_data(

							uid      => $uid,

							db       => $db,

							data     => { trip_id => $trip_id },

							train_id => $train_id,

						);

					}

					return $self->hafas->get_route_p(

						train         => $train,