MarsSeed [1] filed a deletion request for python-blivet-git [2]: Broken. Abandoned. Unused: popularity 0.000000.
Missing a dependency that has already been deleted due to being EOL
and broken.
There are stable packages on AUR for python-blivet{,-gui} that seem to
be in better shape.
[1] https://aur.archlinux.org/account/MarsSeed/
[2] https://aur.archlinux.org/pkgbase/python-blivet-git/
