Issue #6676: Ensure a meaningful exception is raised when attempting

to parse more than one XML document per pyexpat xmlparser instance.
(Original patches by Hirokazu Yamamoto and Amaury Forgeot d'Arc, with
suggested wording by David Gutteridge)

Modules/pyexpat.c

@@ -908,7 +908,7 @@ xmlparse_ParseFile(xmlparseobject *self, PyObject *f)
         void *buf = XML_GetBuffer(self->itself, BUF_SIZE);
         if (buf == NULL) {
             Py_XDECREF(readmethod);
-            return PyErr_NoMemory();
+            return get_parse_result(self, 0);
         }
 
         bytes_read = readinst(buf, BUF_SIZE, readmethod);