BUG #16427: pgsql_tmp - temp files not released

The following bug has been logged on the website:

Bug reference:      16427
Logged by:          Murali Natti
Email address:      murali.natti@gmail.com
PostgreSQL version: 10.5
Operating system:   Red Hat Enterprise Linux Server release 6.10 (Sant
Description:

Hello Team,

We have observed a bug ( I guess ) that temporary files were not deleted
automatically even thought the respective PIDs are not running anymore.

We couldn't take a chance to delete files manually so ended up with
restarting database to clear temp files.

Is this know bug, what could be the reason for this? Can anyone please let
us know?

Thanks,
Murali