When __slots__ are set to a unicode string, make it work the same as
setting a plain string, ie don't expand to single letter identifiers.
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index 0ce7f82..285bd67 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -1816,7 +1816,7 @@
 		/* Have slots */
 
 		/* Make it into a tuple */
-		if (PyString_Check(slots))
+		if (PyString_Check(slots) || PyUnicode_Check(slots))
 			slots = PyTuple_Pack(1, slots);
 		else
 			slots = PySequence_Tuple(slots);