Bug 19487: Refetch the object to get up-to-date values

This has been raised by failures on t/db_dependent/Circulation/issue.t
(thanks tests!)

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
(cherry picked from commit 850243ee2e)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>

C4/Circulation.pm

@@ -2174,6 +2174,9 @@ sub MarkIssueReturned {
         # Update the returndate
         $dbh->do( $query, undef, @bind );
 
+        # We just updated the returndate, so we need to refetch $issue
+        $issue->discard_changes;
+
         # Create the old_issues entry
         my $old_checkout = Koha::Old::Checkout->new($issue->unblessed)->store;