diff -r f3f42a8c3e26 Objects/bytearrayobject.c
--- a/Objects/bytearrayobject.c	Wed Nov 13 12:11:36 2013 +0100
+++ b/Objects/bytearrayobject.c	Wed Nov 13 13:15:47 2013 +0100
@@ -482,8 +482,16 @@ bytearray_setslice_linear(PyByteArrayObj
         }
         /* XXX(nnorwitz): need to verify this can't overflow! */
         if (PyByteArray_Resize(
-                (PyObject *)self, Py_SIZE(self) + growth) < 0)
+                (PyObject *)self, Py_SIZE(self) + growth) < 0) {
+            if (growth < 0) {
+                if (lo == 0)
+                    self->ob_start += growth;
+                else
+                    memmove(buf + hi, buf + lo + bytes_len,
+                            Py_SIZE(self) - hi);
+            }
             return -1;
+        }
         buf = PyByteArray_AS_STRING(self);
         if (growth > 0) {
             /* Make the place for the additional bytes */