This will work (as per Electrum official instructions):
sudo apt-get install python-qt4 python-pip
sudo pip2 install https://download.electrum.org/2.9.3/Electrum-2.9.3.tar.gz
This will install Electrum 2.9.3
Then proceed as per instructions here for stream isolation:
Note: I don’t know whether choosing the latest version over the backport version poses security problems.