Building docbook html from Mac

When I try cmake --build . --target html

I get these kind of errors:

I/O error : Attempt to load network entity http://www.oasis-open.org/docbook/xml/4.3/docbookx.dtd
[...]/igraph/build/doc/arpack.xml:7: warning: failed to load external entity "http://www.oasis-open.org/docbook/xml/4.3/docbookx.dtd"
]>
  ^
[...]/igraph/build/doc/arpack.xml:32: parser error : Entity 'mdash' not defined
<title><function>igraph_blas_ddot</function> &mdash;  Dot product of two vectors

The first error seems to find something like docbook 4.3, even though I have 5.1_1 installed with brew. I also installed xmlto, and also docbooks-xsl, to see if that would fix it.

I work on a macOS 10.14.6, and don’t have the rights to install a newer version.

What happens if you try to open http://www.oasis-open.org/docbook/xml/4.3/docbookx.dtd from a browser? It seems to work for me and it yields a file with 5703 bytes.

It works for me too, but this file should be installed locally (it is for me).

I can just download it and open it, with either curl or safari.

Cellar/docbook/5.1_1/docbook/xml/4.3/docbookx.dtd also exists and is the same file.