https://sources.debian.org/patches/pngtools/0.5~git20220314.1ccca3a-2/bug1013909.patch/

Description: Fix build failure without network access caused by missing local DTD.
Author: Michael Schaller <misch@google.com>
Bug-Debian: https://bugs.debian.org/1013909
Forwarded: no
Reviewed-By: Mathieu Malaterre <malat@debian.org>
Last-Update: 2022-08-11

--- pngtools-1.3.orig/man/docbook/head.sgml
+++ pngtools-1.3/man/docbook/head.sgml
@@ -12,5 +12,4 @@
      (c) Michael Still, 2001
 -->
 
-<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook SGML V4.4//EN"
-   "http://www.oasis-open.org/docbook/sgml/4.4/docbook.dtd">
+<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook V4.4//EN" []>