I have put /etc/lsb-release file for Sparky 3.3. System is detected as Sparky not Debian, but...
It made a new problem, somebody put it on the forum already.
If the system uses my lsb-release file, it needs proper Sparky template.
You can't run Synaptic-> Settings-> Repositories option or 'software-properties-gtk' command.
The output message is:
Error: could not find a distribution template for Sparky/testing
I have removed 'lsb-release' file now, but I'd like to put it back if anyone knows how to fix it.