BUG #15803: Autocomplete issues in new 11.3 and 9.6.13 psql client

The following bug has been logged on the website:

Bug reference: 15803
Logged by: Ken
Email address: ken(dot)karma(at)gmail(dot)com
PostgreSQL version: 11.3
Operating system: Ubuntu 18.04.2 LTS
Description:

I got issue when traing to autocomplete(tab'ing) in new versions, what
working well in old version(9.6. When I tray autocomplete by pushing tab
putton, it takes a space, but attended to autocomplete
postgres(at)karma:~$ psql
psql (11.3 (Ubuntu 11.3-1.pgdg18.04+1), server 9.6.13)
Type "help" for help.

postgres=# select * from pu
postgres-# \q
postgres(at)karma:~$ psql -p5433
psql (11.3 (Ubuntu 11.3-1.pgdg18.04+1))
Type "help" for help.

And my old 9.6.4:
psql (11.3 (Ubuntu 11.3-1.pgdg18.04+1), server 9.6.4)
You are now connected to database "**" as user "***".