kcolford [1] filed a deletion request for slingshot-launcher [2]:

It is a broken package that also breaks building pantheon-session-bzr with an air helper, the maintainer has commented that this package is out of date and should not be used. Please delete to make future installs work.

[1] https://aur.archlinux.org/account/kcolford/ [2] https://aur.archlinux.org/pkgbase/slingshot-launcher/