Created attachment 335520 [details]
A simple query reproducing the issue

Description of problem:
Perl's database interface behaves very strangely on s390x
architecture. After inserting a row into the DB, the SELECT
statement fetches undefs and empty strings. See the example
below.

Version-Release number of selected component (if applicable):
perl-DBI-1.40-9.s390x
perl-DBD-Pg-1.31-6.s390x

How reproducible:
Always

Steps to Reproduce:
1. create table
2. insert row
3. select row
See the attached reproducer for details.
  
Actual results:
$VAR1 = [
          [
            '',
            undef
          ]
        ];

Expected results:
$VAR1 = [
          [
            '0',
            'Pg DBI works OK'
          ]
        ];

Additional info:
The same test works OK on all other architectures.