Two other points:

* This PR is already merged ;-)
* Core developers seem to agree with me that there was a genuine need for taking the `File.expand_path(..., File.dirname(__FILE__))` approach, because a) [Ruby 1.9.2 implemented `require_relative`](http://stackoverflow.com/questions/4325759/is-require-file-expand-path-file-the-best-practice) and b) [Ruby 2.0.0 implemented `__dir__`](https://www.ruby-forum.com/topic/193674)

The only reason we are using `File.expand_path` here is that we are still stuck on Ruby 1.8.7.  But with hindsight, it would be far better to monkey-patch `Kernel` to support `require_relative`.  Seeing a lot of Ruby code which already which does it one way does not mean that is the best way to do it ;-) 

See also http://stackoverflow.com/questions/4333286/ruby-require-vs-require-relative-best-practice-to-workaround-running-in-both