ZP-792 lock on __FILE__ in filestatemachine.

Released under the Affero GNU General Public License (AGPL) version 3.

this prevent possible collision in the future

src/lib/default/filestatemachine.php

@@ -214,7 +214,7 @@ class FileStateMachine implements IStateMachine {
      * @return boolean     indicating if the user was added or not (existed already)
      */
     public function LinkUserDevice($username, $devid) {
-        $mutex = new SimpleMutex();
+        $mutex = new SimpleMutex(__FILE__);
         $changed = false;
 
         // exclusive block
@@ -258,7 +258,7 @@ class FileStateMachine implements IStateMachine {
      * @return boolean
      */
     public function UnLinkUserDevice($username, $devid) {
-        $mutex = new SimpleMutex();
+        $mutex = new SimpleMutex(__FILE__);
         $changed = false;
 
         // exclusive block