Note on "isdef" support being restored but not recommended.
Note on "isdef" support being restored but not recommended.

	* doc/RELEASE-NOTES.txt: Note "isdef" fix, but do not
	recommend its use.

urbiforge/urbi,aldebaran/urbi,urbiforge/urbi,aldebaran/urbi,urbiforge/urbi,aldebaran/urbi,urbiforge/urbi,aldebaran/urbi,aldebaran/urbi,urbiforge/urbi,urbiforge/urbi,aldebaran/urbi,aldebaran/urbi,urbiforge/urbi,urbiforge/urbi,urbiforge/urbi,aldebaran/urbi