title: Composer failed to clone git repo
body: <p>I'm trying to get a development version of a module in my private GitLab repository.</p>
  
  <p>Using what I've found in <a href="https://stackoverflow.com/questions/34781422/is-it-possible-to-install-a-package-from-a-repository-on-gitlab-using-composer">other answers</a>, my project's composer.json is:</p>
  
  <pre><code>{
      "repositories": [
          {
              "type": "composer",
              "url": "https://git.amh.net.au"
          },
          {
              "type": "package",
              "package": {
                  "name": "amh-framework/amh-framework",
                  "version": "dev-develop",
                  "type": "package",
                  "source": {
                      "url": "git.amh.net.au:/var/opt/gitlab/git-data/repositories/amh-framework/amh-framework.git",
                      "type": "git",
                      "reference": "master"
                  }
              }
          }
      ],
  
      "require": {
          "amh-framework/amh-framework": "dev-develop",
      }
  }
  </code></pre>
  
  <p>But when I run <code>composer update</code>, it throws a RuntimeException:</p>
  
  <pre><code>Failed to execute git clone --no-checkout '' '/var/checkouts/reports/reporter/vendor/amh-framework/amh-framework' &amp;&amp; cd '/var/checkouts/reports/reporter/vendor/amh-framework/amh-framework' &amp;&amp; git remote add composer '' &amp;&amp; git fetch composer                                                                                                                                                                                                                                                
  
  fatal: repository '' does not exist
  </code></pre>
  
  <p>The output from <code>composer update -vvv</code> is:</p>
  
  <pre><code>Resolving dependencies through SAT
  Dependency resolution completed in 0.001 seconds
    - Installing amh-framework/amh-framework (dev-develop 4d135f4)
  Executing command (CWD): git --version
      Cloning 4d135f4b01dc896ffc722d8e24cc106d38cb4602
  Executing command (CWD): git clone --no-checkout '' '/var/checkouts/reports/reporter/vendor/amh-framework/amh-framework' &amp;&amp; cd '/var/checkouts/reports/reporter/vendor/amh-framework/amh-framework' &amp;&amp; git remote add composer '' &amp;&amp; git fetch composer
  Executing command (CWD): git --version
  Failed: [RuntimeException] Failed to execute git clone --no-checkout '' '/var/checkouts/reports/reporter/vendor/amh-framework/amh-framework' &amp;&amp; cd '/var/checkouts/reports/reporter/vendor/amh-framework/amh-framework' &amp;&amp; git remote add composer '' &amp;&amp; git fetch composer
  
  fatal: repository '' does not exist
  </code></pre>
  
  <p>So, it does seem to check the repo to get the latest commit (4d135f4b01dc896ffc722d8e24cc106d38cb4602) - but it's failing when cloning.</p>
  
  <p>I can manually clone the project, so it doesn't appear to be permissions:</p>
  
  <pre><code>git clone git.amh.net.au:/var/opt/gitlab/git-data/repositories/amh-framework/amh-framework.git
  </code></pre>
  
  <p>What can I do to fix this?</p>