tests: minor fix in test_locking_simple()

Author: gsmolk

tests/locking.py

@@ -38,6 +38,8 @@ def test_locking_simple(self):
 
         gdb._execute('signal SIGKILL')
 
+        self.validate_pb(backup_dir)
+
         self.assertEqual(
             'OK', self.show_pb(backup_dir, 'node')[0]['status'])