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If you want to add (compatible) PPA to Zesty, via command at least, it goes like this:
add-apt-repository ppa:oibaf/graphics-drivers
ppa:oibaf/graphics-drivers xenial -> /etc/apt/sources.list.d/ppa_oibaf_graphics-drivers.list
...
Success: 'http://ppa.launchpad.net/oibaf/graphics-drivers/ubuntu xenial main' is added to the repositories
There should be 'zesty' instead. And PPA will use xenial dependencies... So just erase 'xenial' and write 'zesty' in the config file or via gui (Software & Updates) manually before updating or installing anything after adding PPA.