I've forced the installation on my machine with `sudo dpkg -i --force-overwrite /var/cache/apt/archives/libxfont1-dev_1%3a1.5.1-1ubuntu0.16.04.1_amd64.deb`.
The two conflicting files were `/usr/share/doc/libxfont-dev/fontlib.html` and `/usr/share/doc/libxfont-dev/fontlib.txt.gz`. So there should be no problem with this workaround.
That said, these packages should be fixed to remove the conflict.
I've forced the installation on my machine with `sudo dpkg -i --force-overwrite /var/cache/ apt/archives/ libxfont1- dev_1%3a1. 5.1-1ubuntu0. 16.04.1_ amd64.deb` .
The two conflicting files were `/usr/share/ doc/libxfont- dev/fontlib. html` and `/usr/share/ doc/libxfont- dev/fontlib. txt.gz` . So there should be no problem with this workaround.
That said, these packages should be fixed to remove the conflict.