fix PR#5914

git-svn-id: http://caml.inria.fr/svn/ocaml/version/4.01@13830 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02
add missing test

git-svn-id: http://caml.inria.fr/svn/ocaml/version/4.01@13831 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02