tests: fixed mkdir() race condition

Author: dg

tests/bootstrap.php

@@ -16,7 +16,8 @@
 
 // create temporary directory
 define('TEMP_DIR', __DIR__ . '/tmp');
-@mkdir(TEMP_DIR); // @ - directory may already exist
+@mkdir(dirname(TEMP_DIR));
+@mkdir(TEMP_DIR);
 
 
 function before(\Closure $function = NULL)