MDL-17094 Allow translators to disable automatic language update duri…

…ng Moodle upgrade.

One needs just add $CFG->skiplangupgrade = true; to their config.php and keep their language pack up-to-date manually. This is intended for lang pack maintainers with CVS access only.

This is backpported from MOODLE_19_STABLE admin/index.php

lib/adminlib.php

@@ -232,16 +232,20 @@ function upgrade_db($version, $release) {
             require_once($CFG->libdir.'/environmentlib.php');
             print_heading(get_string('environment', 'admin'));
             if (!check_moodle_environment($release, $environment_results, true)) {
-                print_box_start('generalbox', 'notice'); // MDL-8330
-                print_string('langpackwillbeupdated', 'admin');
-                print_box_end();
+                if (empty($CFG->skiplangupgrade)) {
+                    print_box_start('generalbox', 'notice'); // MDL-8330
+                    print_string('langpackwillbeupdated', 'admin');
+                    print_box_end();
+                }
                 notice_yesno(get_string('environmenterrorupgrade', 'admin'),
                              'index.php?confirmupgrade=1&confirmrelease=1', 'index.php');
             } else {
                 notify(get_string('environmentok', 'admin'), 'notifysuccess');
-                print_box_start('generalbox', 'notice'); // MDL-8330
-                print_string('langpackwillbeupdated', 'admin');
-                print_box_end();
+                if (empty($CFG->skiplangupgrade)) {
+                    print_box_start('generalbox', 'notice'); // MDL-8330
+                    print_string('langpackwillbeupdated', 'admin');
+                    print_box_end();
+                }
                 echo '<form action="index.php"><div>';
                 echo '<input type="hidden" name="confirmupgrade" value="1" />';
                 echo '<input type="hidden" name="confirmrelease" value="1" />';
@@ -290,7 +294,9 @@ function upgrade_db($version, $release) {
             upgrade_log_start();
 
         /// Upgrade current language pack if we can
-            upgrade_language_pack();
+            if (empty($CFG->skiplangupgrade)) {
+                upgrade_language_pack();
+            }
 
             print_heading($strdatabasechecking);
             $DB->set_debug(true);