Don't apply substitution from ancestor if class defines its own type variable (PY-27783)

python/testSrc/com/jetbrains/python/Py3TypeTest.java

@@ -953,6 +953,27 @@ public class Py3TypeTest extends PyTestCase {
     );
   }
 
+  // PY-27783
+  public void testApplyingSuperSubstituionToGenericClass() {
+    runWithLanguageLevel(
+      LanguageLevel.PYTHON36,
+      () -> doTest("Dict[T, int]",
+                   "from typing import TypeVar, Generic, Dict, List\n" +
+                   "\n" +
+                   "T = TypeVar('T')\n" +
+                   "\n" +
+                   "class A(Generic[T]):\n" +
+                   "    pass\n" +
+                   "\n" +
+                   "class B(A[List[T]], Generic[T]):\n" +
+                   "    def __init__(self) -> None:\n" +
+                   "        self.value_set: Dict[T, int] = {}\n" +
+                   "\n" +
+                   "    def foo(self) -> None:\n" +
+                   "        expr = self.value_set")
+    );
+  }
+
   private void doTest(final String expectedType, final String text) {
     myFixture.configureByText(PythonFileType.INSTANCE, text);
     final PyExpression expr = myFixture.findElementByText("expr", PyExpression.class);