BUG #14813: pg_get_serial_sequence does not return seqence name for IDENTITY columns

The following bug has been logged on the website:

Bug reference: 14813
Logged by: zam zam
Email address: zam6ak(at)gmail(dot)com
PostgreSQL version: 10beta4
Operating system: windows
Description:

Function pg_get_serial_sequence returns NULL on columns defined as
IDENTITY

CREATE TABLE IF NOT EXISTS public.test (
id bigint NOT NULL GENERATED ALWAYS AS IDENTITY,
code text,

CONSTRAINT test_pk PRIMARY KEY (id)
)

SELECT pg_get_serial_sequence('public.test', 'id'); -- returns NULL instead
of 'test_id_seq'!