🐛 Fixes renaming of args and kwargs with python <3.4

If the new name for `*args` happened to be the same as the old name for `**kwargs`,
renaming `**kwargs` would incorrectly also rename `*args`.

src/python_minifier/rename/binding.py

@@ -235,10 +235,15 @@ def rename(self, new_name):
                 node.names = [new_name if n == self._name else n for n in node.names]
             elif isinstance(node, ast.arguments):
 
-                if node.vararg == self._name:
+                rename_vararg = (node.vararg == self._name) and not getattr(node, 'vararg_renamed', False)
+                rename_kwarg = (node.kwarg == self._name) and not getattr(node, 'kwarg_renamed', False)
+
+                if rename_vararg:
                     node.vararg = new_name
-                if node.kwarg == self._name:
+                    node.vararg_renamed = True
+                if rename_kwarg:
                     node.kwarg = new_name
+                    node.kwarg_renamed = True
 
         self._name = new_name
 

test/test_rename_locals.py

@@ -298,3 +298,15 @@ def t():
     expected_ast = ast.parse(expected)
     actual_ast = rename_locals(source)
     assert_code(expected_ast, actual_ast)
+
+def test_arg_rename():
+
+    source = '''
+def f(*B,**A):pass
+'''
+    expected = '''
+def f(*A,**B):pass
+'''
+    expected_ast = ast.parse(expected)
+    actual_ast = rename_locals(source)
+    assert_code(expected_ast, actual_ast)