[xml/sgml-pkgs] Bug#410713: libxml2-dev unmet dependencies won't install

[wbd]

Package: libxml2-dev
Version: 2.6.16-7

I've been trying to install libxml2-dev on sarge using apt-get as follows

sudo apt-get install libxml2-dev

I get the following as output

    Reading Package Lists...
    Building Dependency Tree...
    Some packages could not be installed. This may mean that you have
    requested an impossible situation or if you are using the unstable
    distribution that some required packages have not yet been created
    or been moved out of Incoming.

    Since you only requested a single operation it is extremely likely that
    the package is simply not installable and a bug report against
    that package should be filed.
    The following information may help to resolve the situation:

    The following packages have unmet dependencies:
      libxml2-dev: Depends: libxml2 (= 2.6.16-7) but 2.6.20-1 is to be
    installed
    E: Broken Packages


My sources.list looks like this

    deb http://www.debian-multimedia.org sarge main
    deb http://http.us.debian.org/debian sarge main contrib non-free

Before trying the apt-get command above I did an apt-get update, apt-get 
upgrade

apt-config dump gives

    APT "";
    APT::Architecture "i386";
    APT::Build-Essential "";
    APT::Build-Essential:: "build-essential";
    Dir "/";
    Dir::State "var/lib/apt/";
    Dir::State::lists "lists/";
    Dir::State::cdroms "cdroms.list";
    Dir::State::userstatus "status.user";
    Dir::State::status "/var/lib/dpkg/status";
    Dir::Cache "var/cache/apt/";
    Dir::Cache::archives "archives/";
    Dir::Cache::srcpkgcache "srcpkgcache.bin";
    Dir::Cache::pkgcache "pkgcache.bin";
    Dir::Etc "etc/apt/";
    Dir::Etc::sourcelist "sources.list";
    Dir::Etc::vendorlist "vendors.list";
    Dir::Etc::vendorparts "vendors.list.d";
    Dir::Etc::main "apt.conf";
    Dir::Etc::parts "apt.conf.d";
    Dir::Etc::preferences "preferences";
    Dir::Bin "";
    Dir::Bin::methods "/usr/lib/apt/methods";
    Dir::Bin::dpkg "/usr/bin/dpkg";
    DPkg "";
    DPkg::Pre-Install-Pkgs "";
    DPkg::Pre-Install-Pkgs:: "/usr/sbin/dpkg-preconfigure --apt || true";