Matthewacon [1] filed a deletion request for stunnel-systemd-git [2]: I no longer maintain the underlying fork of stunnel for this package, nor the PKGBUILD. There are also no usages of this package.
[1] https://aur.archlinux.org/account/Matthewacon/ [2] https://aur.archlinux.org/pkgbase/stunnel-systemd-git/
