Only insert the institution expiries cronjob if it hasn't been before.

Signed-off-by: Nigel McNie <nigel@catalyst.net.nz>

htdocs/lib/db/upgrade.php

@@ -889,14 +889,16 @@ function xmldb_core_upgrade($oldversion=0) {
         add_field($table, $suspended);
 
         // Insert a cron job to check for soon expiring and expired institutions
-        $cron = new StdClass;
-        $cron->callfunction = 'auth_handle_institution_expiries';
-        $cron->minute       = '5';
-        $cron->hour         = '9';
-        $cron->day          = '*';
-        $cron->month        = '*';
-        $cron->dayofweek    = '*';
-        insert_record('cron', $cron);
+        if (!record_exists('cron', 'callfunction', 'auth_handle_institution_expiries')) {
+            $cron = new StdClass;
+            $cron->callfunction = 'auth_handle_institution_expiries';
+            $cron->minute       = '5';
+            $cron->hour         = '9';
+            $cron->day          = '*';
+            $cron->month        = '*';
+            $cron->dayofweek    = '*';
+            insert_record('cron', $cron);
+        }
     }
 
     if ($oldversion < 2009031800) {