It is not clear in what order what order gems are checked for with $ "bundle show". It's not alphabetical nor the Gemfile order. It would also be nice to know how many (which ones / all) are missing (instead of a seemingly random one-at-a-time). Here is the context of my issue http://groups.google.com/group/heroku/browse_thread/thread/4752ee7b132a30d6 with this.
The new repo is here: http://github.com/carlhuda/bundler
And a similar issue here: http://github.com/carlhuda/bundler/issues/closed#issue/98