Comment 6 for bug 1313973

The work around I managed for Ubuntu 15.10, is similar to as suggested by @AngelPerez, though with a slight modification as follows:

Firstly I created a backup of /var/lib/dpkg/info/websvn.postinst as follows:

sudo cp -r /var/lib/dpkg/info/websvn.postinst /var/lib/dpkg/info/websvn_original.postinst

Then I modified the contents as follows:

sudo vim /var/lib/dpkg/info/websvn.postinst

OLD:
if [ ! -f /etc/$webserver/conf.d/websvn ] && [ ! -h /etc/$webserver/conf.d/websvn ]; then
        ln -s /etc/websvn/apache.conf /etc/$webserver/conf.d/websvn
        restart="$restart $webserver"
fi

NEW:
if [ ! -f /etc/$webserver/conf.d/websvn ] && [ ! -h /etc/$webserver/conf.d/websvn ]; then
        ln -s /etc/websvn/apache.conf /etc/$webserver/sites-available/websvn.conf
        sudo a2ensite websvn
        restart="$restart $webserver"
fi

Now I forced installed websvn with:

sudo apt-get -f install websvn

Now I copied apache.conf from websvn to websvn.conf inside apache2 as follows:

sudo cp -r /etc/websvn/apache.conf /etc/apache2/sites-available/websvn.conf

Restarted my apache2

sudo systemctl restart apache2

That is it. It started working after this :-)