Bug #1486663: don't reject keyword arguments for subclasses of builtin
types.
 (backport from rev. 53509)
diff --git a/Lib/test/test_deque.py b/Lib/test/test_deque.py
index 35e1536..1d996ee 100644
--- a/Lib/test/test_deque.py
+++ b/Lib/test/test_deque.py
@@ -486,6 +486,16 @@
         d1 == d2   # not clear if this is supposed to be True or False,
                    # but it used to give a SystemError
 
+
+class SubclassWithKwargs(deque):
+    def __init__(self, newarg=1):
+        deque.__init__(self)
+
+class TestSubclassWithKwargs(unittest.TestCase):
+    def test_subclass_with_kwargs(self):
+        # SF bug #1486663 -- this used to erroneously raise a TypeError
+        SubclassWithKwargs(newarg=1)
+
 #==============================================================================
 
 libreftest = """
@@ -599,6 +609,7 @@
         TestBasic,
         TestVariousIteratorArgs,
         TestSubclass,
+        TestSubclassWithKwargs,
     )
 
     test_support.run_unittest(*test_classes)