I must be missing something obvious, this is from a clean checkout of celluloid-io.
[!] There was an error parsing `Gemfile`: cannot load such file -- /Users/dblock/source/celluloid/celluloid-io/celluloid/culture/sync. Bundler cannot continue.
# from /Users/dblock/source/celluloid/celluloid-io/celluloid/Gemfile:2
# -------------------------------------------
# puts File.expand_path("../culture/sync", __FILE__)
> require File.expand_path("../culture/sync", __FILE__)
#
# -------------------------------------------