This is un-defined.patch from https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=657144
See also: https://rt.cpan.org/Ticket/Display.html?id=74354

diff -ru libunicode-string-perl-2.09.pristine/lib/Unicode/CharName.pm libunicode-string-perl-2.09/lib/Unicode/CharName.pm
--- libunicode-string-perl-2.09.pristine/lib/Unicode/CharName.pm	2005-10-25 19:11:00.000000000 +0100
+++ libunicode-string-perl-2.09/lib/Unicode/CharName.pm	2012-01-24 12:56:59.730653088 +0000
@@ -77,7 +77,7 @@
 	    return join("", "HANGUL SYLLABLE ", @s)
 	}
     }
-    _init_names() unless defined %NAMES;
+    _init_names() unless %NAMES;
     $NAMES{sprintf("%04X",$code)}
 }