Keep polls with bad expiration date in database

(cherry picked from commit c15ce049)

Conflicts:
	app/classes/Framadate/Utils.php

app/classes/Framadate/FramaDB.php

@@ -268,7 +268,7 @@ class FramaDB {
      * @return array Array of old polls
      */
     public function findOldPolls() {
-        $prepared = $this->prepare('SELECT * FROM ' . Utils::table('poll') . ' WHERE end_date < NOW() LIMIT 20');
+        $prepared = $this->prepare('SELECT * FROM ' . Utils::table('poll') . ' WHERE end_date < NOW() AND date_fin != 0 LIMIT 20');
         $prepared->execute([]);
 
         return $prepared->fetchAll();