BUG #15795: ERROR: could not find pathkey item to sort

The following bug has been logged on the website:

Bug reference: 15795
Logged by: Suresh Kumar R
Email address: suresh(dot)arsenal29(at)gmail(dot)com
PostgreSQL version: 10.3
Operating system: Ubuntu 16.04
Description:

I have a table 'person' with properties _id, _actual_type_name and name when
I tried the below query, I got an error saying 'could not find pathkey item
to sort'.

Here is query:
SELECT DISTINCT A._id0 as _id0, A._actual_type_name0 as _actual_type_name0
FROM ( ( SELECT DISTINCT _id as _id0, _actual_type_name as
_actual_type_name0, name as name0 FROM hello_world.person ) union all (
SELECT DISTINCT _id as _id0, _actual_type_name as _actual_type_name0, name
as name0 FROM hello_world.person)) as A WHERE ( A.name0 = A.name0 );