Crash on UNION with PG 17

[Regina Obe]

Our PostGIS bot that follows master branch has been crashing for past couple
of days on one of our tests

https://trac.osgeo.org/postgis/ticket/5701

I traced the issue down to this commit:
https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=66c0185a3d14b
bbf51d0fc9d267093ffec735231


The issue can be exercised without postgis installed as follows:


CREATE TABLE edge_data AS 
SELECT i AS edge_id, i + 1 AS start_node, i + 2 As end_node
FROM generate_series(1,10) AS i;

  WITH edge AS (
    SELECT start_node, end_node
    FROM edge_data
    WHERE edge_id = 1
  )
  SELECT start_node id FROM edge UNION
  SELECT end_node FROM edge;


If I run using UNION ALL, this works fine:

  WITH edge AS (
    SELECT start_node, end_node
    FROM edge_data
    WHERE edge_id = 1
  )
  SELECT start_node id FROM edge UNION ALL
  SELECT end_node FROM edge;


Thanks,
Regina