maintenance: backpropagate polylines to route entries using pre-1.9.4 format

		$db->select( 'journeys', [ 'id', 'route' ], { polyline_id => undef } )

		->hashes->each )

	{

		# prior to v1.9.4, routes were stored as [["stop1"], ["stop2"], ...].

		# Nowadays, the common format is [["stop1", {}, null], ...].

		# entry[1] is non-empty only while checked in, entry[2] is non-null only

		# if the stop is unscheduled or has been cancelled.

		#

		# Here, we pretened to use the new format, as we're looking for

		# matching routes in more recent journeys.

		#

		# Note that journey->{route} is serialized JSON (i.e., a string).

		# It is not deserialized for performance reasons.

		$journey->{route}

		  =~ s/ (?<! additional ) (?<! cancelled ) "] /", {}, null]/gx;

		my $ref = $db->select(

			'journeys',

			[ 'id', 'polyline_id' ],