opscode/chef — pull request #178 by pcn (2011-11-08 05:23:58+00:00)
Title: Config option to allow for knifing a knew host with a 

My testing copy of .chef/knife.rb normally sets it this way, to use a local version (per chef config):
data_bag_keyfile "#{current_dir}/data_bag_key"

More info in the mailing list post at http://lists.opscode.com/sympa/arc/chef/2011-11/msg00071.html.