Otherwise functions that require collation information will not have
it if they are called in arguments to a CALL statement.
Reported-by: Jean-Marc Voillequin <Jean-Marc.Voillequin@moodys.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://www.postgresql.org/message-id/flat/1EC8157EB499BF459A516ADCF135ADCE39FFAC54%40LON-WGMSX712.ad.moodys.net