fix object.__eq__ to give the other side a chance to do the comparison

Author: timfel

graalpython/com.oracle.graal.python.test/src/tests/unittest_tags/test_binop.txt

@@ -1,4 +1,5 @@
 *graalpython.lib-python.3.test.test_binop.FallbackBlockingTests.test_fallback_ne_blocking
+*graalpython.lib-python.3.test.test_binop.FallbackBlockingTests.test_fallback_rmethod_blocking
 *graalpython.lib-python.3.test.test_binop.OperationOrderTests.test_comparison_orders
 *graalpython.lib-python.3.test.test_binop.RatTestCase.test_add
 *graalpython.lib-python.3.test.test_binop.RatTestCase.test_constructor

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/object/ObjectBuiltins.java

@@ -234,8 +234,15 @@ public int hash(Object self) {
     public abstract static class EqNode extends PythonBinaryBuiltinNode {
         @Specialization
         Object eq(Object self, Object other,
+                        @Cached ConditionProfile isEq,
                         @Cached IsNode isNode) {
-            return isNode.execute(self, other);
+            if (isEq.profile(isNode.execute(self, other))) {
+                return true;
+            } else {
+                // Return NotImplemented instead of False, so if two objects are compared, both get
+                // a chance at the comparison
+                return PNotImplemented.NOT_IMPLEMENTED;
+            }
         }
     }