Add PY_SSIZE_T_MIN, as suggested by Ralf W. Grosse-Kunstleve.
diff --git a/Objects/longobject.c b/Objects/longobject.c
index ebcce45c..26f78c2 100644
--- a/Objects/longobject.c
+++ b/Objects/longobject.c
@@ -281,7 +281,7 @@
 	if (sign > 0) 
 		return PY_SSIZE_T_MAX;
 	else 
-		return -PY_SSIZE_T_MAX-1;
+		return PY_SSIZE_T_MIN;
 }
 
 /* Get a Py_ssize_t from a long int object.