amd-fx@amd-fx:~$ sudo apt-get build-dep pcsx2-unstable
[sudo] password for amd-fx: 
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Picking 'pcsx2.snapshot' as source package instead of 'pcsx2-unstable'
E: Unable to find a source package for pcsx2.snapshot
amd-fx@amd-fx:~$