Index: Python/pythonrun.c
===================================================================
--- Python/pythonrun.c	(revision 62084)
+++ Python/pythonrun.c	(working copy)
@@ -1273,8 +1273,15 @@
 	Py_DECREF(value);
 	/* If an error happened here, don't show it.
 	   XXX This is wrong, but too many callers rely on this behavior. */
-	if (err != 0)
+	if (err != 0) {
+		/* Warn about parts of the exception not displayed */
+		if (PyErr_Occurred() &&
+			PyErr_ExceptionMatches(PyExc_UnicodeEncodeError))
+			PyErr_WarnEx(PyExc_UnicodeWarning,
+			"The exception and/or traceback could not be encoded properly.",
+			2);
 		PyErr_Clear();
+	}
 }
 
 PyObject *