Unable to build polkit

[tr%vispaul.me@localhost]

Hello pkgsrc-users,

I'm currently unable to build polkit (0.113 in 2018Q1 and 0.114 in 
current) on NetBSD 7.1.2 without adding the following to the Makefile:

  CONFIGURE_ARGS+=    --disable-man-pages

The build fails with:

  /opt/pkg/bin/xsltproc -nonet --stringparam 
man.base.url.for.relative.links /opt/pkg/share/gtk-doc/html/polkit-1/ 
--xinclude http://docbook.sourceforge.net/release/xsl/current/man
  pages/docbook.xsl polkit.xml
  I/O error : Attempt to load network entity 
http://docbook.sourceforge.net/release/xsl/current/manpages/docbook.xsl
  warning: failed to load external entity 
"http://docbook.sourceforge.net/release/xsl/current/manpages/docbook.xsl";
  cannot parse 
http://docbook.sourceforge.net/release/xsl/current/manpages/docbook.xsl
  Makefile:647: recipe for target 'polkit.8' failed

At first, I thought it was due to a network timeout, however, I have no 
issues manually fetching the XSL file (e.g., with curl or firefox). I've 
attempted many times to build the package, and it always fails at this 
point.

Does someone know of another solution to work around this issue? Is 
anyone else having the same problem? My mk.conf is rather uninteresting, 
I do have PKG_DEVELOPER=yes set.

Thanks in advance,
Travis