Same problem here, after upgrading tvheadend encrypted channels stopped working after a couple of seconds, with an access denied message. Rolling back to commit 39b6bc1d worked for me.
aptitude install git build-essential debhelper libavahi-client-dev libssl-dev zlib1g-dev libcurl4-gnutls-dev liburiparser-dev
cd /usr/local/src/
git clone https://github.com/tvheadend/tvheadend
cd tvheadend/
git checkout 39b6bc1d
./Autobuild.sh
cd ..
dpkg -i tvheadend_3.9.1070~g39b6bc1_amd64.deb
Hope it will be fixed in a future release :)