Fix style.

dulwich/porcelain.py

@@ -481,7 +481,8 @@ def clean(repo=".", target_dir=None):
             raise Error("target_dir must be in the repo's working dir")
 
         config = r.get_config_stack()
-        require_force = config.get_boolean((b'clean',), b'requireForce', True)
+        require_force = config.get_boolean(   # noqa: F841
+            (b'clean',), b'requireForce', True)
 
         # TODO(jelmer): if require_force is set, then make sure that -f, -i or
         # -n is specified.