Merge branch 'MDL-70137-39-2' of git://github.com/andrewnicols/moodle into MOODLE_39_STABLE

cache/classes/config.php

@@ -323,7 +323,7 @@ class cache_config {
      * @throws cache_exception
      */
     protected function include_configuration() {
-        $configuration = array();
+        $configuration = null;
         // We need to allow for late static bindings to allow for class path mudling happending for unit tests.
         $cachefile = static::get_config_file_path();
 
@@ -594,4 +594,4 @@ class cache_config {
         }
         throw new cache_exception('ex_nodefaultlock');
     }
-}
+}

cache/locallib.php

@@ -102,13 +102,15 @@ class cache_config_writer extends cache_config {
         $factory = cache_factory::instance();
         $locking = $factory->create_lock_instance($lockconf);
         if ($locking->lock('configwrite', 'config', true)) {
+            $tempcachefile = "{$cachefile}.tmp";
             // Its safe to use w mode here because we have already acquired the lock.
-            $handle = fopen($cachefile, 'w');
+            $handle = fopen($tempcachefile, 'w');
             fwrite($handle, $content);
             fflush($handle);
             fclose($handle);
             $locking->unlock('configwrite', 'config');
-            @chmod($cachefile, $CFG->filepermissions);
+            @chmod($tempcachefile, $CFG->filepermissions);
+            rename($tempcachefile, $cachefile);
             // Tell PHP to recompile the script.
             core_component::invalidate_opcode_php_cache($cachefile);
         } else {