The package stopped building for some unknown reason (npm could no
longer fetch a module).
This is one of the build failures listed in #23253.
http://hydra.nixos.org/build/49551309http://hydra.nixos.org/build/49548753
Easiest fix is to upgrade to latest stable version and regenerate
packages with node2nix.
The databank-memcached dependency needed to be dropped due to
dependency failures.