The shairport-sync service currently fails to start with the error
shairport avahi_entry_group_new failed
This problem seems to have been introduced by
cdd7310a50
After some trial and error I concluded that the attached commit is a minimal
fix.
*** NixOS *** NixOS is a Linux distribution based on the purely functional package management system Nix. More information can be found at http://nixos.org/nixos and in the manual in doc/manual.