pgsql: Fix MERGE into a plain inheritance parent table.

Fix MERGE into a plain inheritance parent table. When a MERGE's target table is the parent of an inheritance tree, any INSERT actions insert into the parent table using ModifyTableState's rootResultRelInfo. However, there are two bugs in the way this is initialized: 1. ExecInitMerge() incorrectly

pgsql: Fix MERGE into a plain inheritance parent table.

Fix MERGE into a plain inheritance parent table. When a MERGE's target table is the parent of an inheritance tree, any INSERT actions insert into the parent table using ModifyTableState's rootResultRelInfo. However, there are two bugs in the way is initialized: 1. ExecInitMerge() incorrectly uses

pgsql: Fix MERGE into a plain inheritance parent table.

Fix MERGE into a plain inheritance parent table. When a MERGE's target table is the parent of an inheritance tree, any INSERT actions insert into the parent table using ModifyTableState's rootResultRelInfo. However, there are two bugs in the way this is initialized: 1. ExecInitMerge() incorrectly

pgsql: Fix MERGE into a plain inheritance parent table.

Fix MERGE into a plain inheritance parent table. When a MERGE's target table is the parent of an inheritance tree, any INSERT actions insert into the parent table using ModifyTableState's rootResultRelInfo. However, there are two bugs in the way this is initialized: 1. ExecInitMerge() incorrectly