Fix cherry-pick

Author: Ivan Levkivskyi

test-data/unit/check-classes.test

@@ -2759,7 +2759,7 @@ t = Test()
 t.crash = 'test'  # E: "Test" has no attribute "crash"
 
 class A:
-    def __setattr__(self): ...  # E: Invalid signature "def (__main__.A) -> Any" for "__setattr__"
+    def __setattr__(self): ...  # E: Invalid signature "def (self: __main__.A) -> Any" for "__setattr__"
 a = A()
 a.test = 4  # E: "A" has no attribute "test"
 
@@ -2769,7 +2769,7 @@ b = B()
 b.integer = 5
 
 class C:
-    def __setattr__(self, name: int, value: int) -> None: ...  # E: Invalid signature "def (__main__.C, builtins.int, builtins.int)" for "__setattr__"
+    def __setattr__(self, name: int, value: int) -> None: ...  # E: Invalid signature "def (self: __main__.C, name: builtins.int, value: builtins.int)" for "__setattr__"
 c = C()
 c.check = 13