Fix duplicate rows in Gather after Append removed

When Who What
2022-01-25 09:29:47 Yura Sokolov (funny_falcon) Closed in commitfest 2022-01 with status: Committed
2022-01-25 09:29:47 Yura Sokolov (funny_falcon) Changed committer to davidrowley
2022-01-23 11:58:03 Yura Sokolov (funny_falcon) Changed authors to David Rowley (davidrowley), Yura Sokolov (funny_falcon)
2021-12-30 11:17:22 Yura Sokolov (funny_falcon) Changed authors to Yura Sokolov (funny_falcon)
2021-12-30 11:17:22 Yura Sokolov (funny_falcon) Changed targetversion to stable
2021-12-30 11:16:20 Yura Sokolov (funny_falcon) Attached mail thread b59605fecb20ba9ea94e70ab60098c237c870628.camel@postgrespro.ru
2021-12-30 11:16:20 Yura Sokolov (funny_falcon) Created patch record