title: composer update not pulling latest dev-master
body: <p>I've created two git repositories that we need to install in one of our web applications by using PHP's <strong>composer</strong>. There are two branches on each repository, <strong>master</strong> and <strong>dev-master</strong>.</p>
  
  <p>Inside the project I want the package to install, I've created the following composer.json package configuration:    </p>
  
  <pre><code>{
      "name": "laravel/laravel",
      "description": "The Laravel Framework.",
      "keywords": ["framework", "laravel"],
      "license": "proprietary",
      "repositories": [
          {
              "type": "package",
              "package": {
                  "name": "impression-works/pdf-generator",
                  "version": "dev-master",
                  "source": {
                      "url": "git@github.com:...",
                      "type": "git",
                      "reference": "dev-master"
                  }
              }
          },
          {
              "type": "package",
              "package": {
                  "name": "impression-works/psd-templates",
                  "version": "dev-master",
                  "source": {
                      "url": "git@github.com:...",
                      "type": "git",
                      "reference": "dev-master"
                  }
              }
          }
      ],
      "require": {
          // ...
          "impression-works/psd-templates": "dev-master",
          "impression-works/pdf-generator": "dev-master"
      },
      "autoload": {
          // ...
          "psr-0": {
              "ImpressionWorks\\PsdTemplates": "vendor/impression-works/psd-templates/src",
              "ImpressionWorks\\PdfGenerator": "vendor/impression-works/pdf-generator/src"
          }
      },
      // ...
      "config": {
          "preferred-install": "dist"
      },
      "minimum-stability": "stable"
  }
  </code></pre>
  
  <p>When I initially run composer update or composer install, the impression-works packages install perfectly, however, if I make changes to these repositories, and push them to dev-master, any successive calls to composer update simply reports:</p>
  
  <pre><code>Nothing to install or update
  </code></pre>
  
  <p>How do I force composer to update to the latest commit on these two custom packages of ours?</p>