classobject.c:instancemethod_descr_get(): when a bound method is
assigned to a class variable and then accessed via an instance, it
should not be rebound.

test_descr.py:methods(): test for the condition above.
diff --git a/Lib/test/test_descr.py b/Lib/test/test_descr.py
index 4d1f817..f524dba 100644
--- a/Lib/test/test_descr.py
+++ b/Lib/test/test_descr.py
@@ -862,7 +862,7 @@
     d2 = D(2)
     verify(d2.foo() == 2)
     verify(d2.boo() == 2)
-    verify(d2.goo() == 2)
+    verify(d2.goo() == 1)
 
 def specials():
     # Test operators like __hash__ for which a built-in default exists