BUG #17957: psql-16beta1 \df+ does not show the function body

The following bug has been logged on the website:

Bug reference:      17957
Logged by:          Boris Z
Email address:      bzm@2bz.de
PostgreSQL version: 16beta1
Operating system:   OSX, Linux
Description:

Hi,

The release notes do not mention \df+. 
https://www.postgresql.org/docs/16/release-16.html#RELEASE-16-PSQL

for testing I used this function, but any user function will do.

CREATE OR REPLACE FUNCTION test_function()
RETURNS bigint
AS $$
    SELECT 1;
$$ LANGUAGE sql
STABLE
PARALLEL SAFE;

When using psql (16beta1)
=# \df+ test_function
-[ RECORD 1 ]-------+--------------
Schema              | public
Name                | test_function
Result data type    | bigint
Argument data types |
Type                | func
Volatility          | stable
Parallel            | safe
Owner               | bz
Security            | invoker
Access privileges   |
Language            | sql
Internal name       |
Description         |

using psql-15.3 it works as expected
=# \df+ test_function
-[ RECORD 1 ]-------+--------------
Schema              | public
Name                | test_function
Result data type    | bigint
Argument data types |
Type                | func
Volatility          | stable
Parallel            | safe
Owner               | bz
Security            | invoker
Access privileges   |
Language            | sql
Source code         |              +
                    |     SELECT 1;+
                    |
Description         |