EllisLab/CodeIgniter — pull request #1356 by thanpolas (2012-05-14 18:33:56+00:00)
Title: New config load sequence

Load the config.php from base config directory, then load any config in the environment directory.

This in effect causes the keys in environment's config to overwrite base ones, allowing to have config.php files with only the keys we want changed, instead having to copy/paste the whole config.php and edit the few keys we want changed per environment.