Use self git-fork in composer

README.md

"behat/behat" is the original library and "dev-fork" is the branch is needed. "rakauchuk/Behat" is a fork of "dev-master" branch. "composer update" should get the modified version of "behat/behat"

composer.json

{
  "name": "",
  "license": "proprietary",
  "description": "",
  "repositories": [
    {
      "type": "vcs",
      "url": "https://github.com/rakauchuk/Behat"
    }
  ],
  "require": {
    "behat/behat": "dev-master"
  },
  "minimum-stability": "dev",
  "prefer-stable": true,
  "config": {
    "bin-dir": "bin/"
  }
}