bpo-37417: Fix error handling in bytearray.extend.

Lib/test/test_builtin.py

@@ -1592,6 +1592,11 @@ def test_bytearray_translate(self):
         self.assertRaises(ValueError, x.translate, b"1", 1)
         self.assertRaises(TypeError, x.translate, b"1"*256, 1)
 
+    def test_bytearray_extend_error(self):
+        array = bytearray()
+        bad_iter = map(int, "X")
+        self.assertRaises(ValueError, array.extend, bad_iter)
+
     def test_construct_singletons(self):
         for const in None, Ellipsis, NotImplemented:
             tp = type(const)

Misc/NEWS.d/next/Core and Builtins/2019-06-26-18-41-00.bpo-37417.VsZeHL.rst

@@ -0,0 +1,2 @@
+:meth:`bytearray.extend` now correctly handles errors that arise during iteration.
+Patch by Brandt Bucher.

Objects/bytearrayobject.c

@@ -1698,6 +1698,10 @@ bytearray_extend(PyByteArrayObject *self, PyObject *iterable_of_ints)
     }
     Py_DECREF(bytearray_obj);
 
+    if (PyErr_Occurred()) {
+        return NULL;
+    }
+
     Py_RETURN_NONE;
 }