BUG #13623: " authentication_timeout " is invalid.

The following bug has been logged on the website:

Bug reference:      13623
Logged by:          postgresql.conf 's " authentication_timeout " is invalid.
Email address:      james.lin@cenoq.com
PostgreSQL version: 9.5alpha2
Operating system:   RHEL6.4
Description:

Hi, sir,

the "postgresql.conf" 's "authentication_timeout"  is not active.

The example Log:
-------------------------------------------------------------------------------------------------
[BEGIN] 2015/9/16  17:57:37
[postgres@pg95 ~]$ psql -V
psql (PostgreSQL) 9.5alpha2
[postgres@pg95 ~]$ time psql -c 'show authentication_timeout ;'
Password:
 authentication_timeout
------------------------
 1min
(1 row)
real    4m39.528s
user    0m0.003s
sys    0m0.002s

[END] 2015/9/16  18:03:10
---------------------------------------------------------------------------------------------------
The document is said :
From:

http://www.postgresql.org/docs/9.4/static/runtime-config-connection.html

authentication_timeout (integer)
Maximum time to complete client authentication, in seconds. If a would-be
client has not completed the authentication protocol in this much time, the
server closes the connection. This prevents hung clients from occupying a
connection indefinitely. The default is one minute (1m). This parameter can
only be set in the postgresql.conf file or on the server command line.


I can't find about this information or solution by goolge search or forum,
Please tell me how to verify it is active . or check it  running? thanks.