[Pkg-phototools-devel] Bug#1013909: pngtools: Package fails to build without network access

[Michael Schaller]

> To fix this issue you need to make the DTD available locally. For example see the `openjade` package, particularly `/etc/sgml/openjade.cat` and `/usr/share/sgml/OpenJade/`.
>
It looks like the DTD is already available locally if the `docbook`
package is installed. The missing DTD is then available under
`/usr/share/sgml/docbook/dtd/4.4/docbook.dtd`.
However just adding `docbook` as build dependency isn't enough to fix
the build failure.