Bug 33567: Add a dbrev for installation with empty pref

To keep current behavior, we can copy the removed fallback
into the syspref value in case someone might have cleared the pref.

Note: We are not restoring deleted prefs here; that is a data problem
outside the scope of this report. A regular installation should always
have this pref.

Test plan:
Run updatedatabase.pl
Bonus: Clear the pref Reference_NFL_Statuses and run again, verify that
the pref has changed.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>

installer/data/mysql/atomicupdate/bug_33567.pl

@@ -0,0 +1,17 @@
+use Modern::Perl;
+
+return {
+    bug_number => 33567,
+    description => "Replace empty Reference_NFL_Statuses pref",
+    up => sub {
+        my ($args) = @_;
+        my ($dbh, $out) = @$args{qw(dbh out)};
+
+        my $rv = $dbh->do(q{
+            UPDATE systempreferences SET value='1|2'
+            WHERE variable = 'Reference_NFL_Statuses' AND COALESCE(value,'')=''
+        });
+        say $out "Updated preference Reference_NFL_Statuses to default"
+            if $rv && $rv == 1;
+    },
+};