If you run into a situation that
rake gems:unpack silently skips some gems, check if those gems provide rake tasks. When Rakefile is loaded, vendor/gems is not yet added to load path so Rails doesn’t try to unpack those gems. For example when you run generator for hoptoad_notifier it adds
tasks/hoptoad_notifier_tasks.rake to your Rails project. If you try to unpack it after that, it doesn´t work.
You can either run
rake gems:unpack before running the generator and adding the rake tasks or comment out the rake tasks temporarily and uncomment them after unpacking the gem. In hoptoad_notifier´s case you would comment out
require 'hoptoad_notifier/tasks' in the