title: Create a new Git repository from current HEAD, set it as a remote of the original, and mirror future changes to both repositories?
body: <p>The current repository has commits </p>
  
  <pre><code>  A -&gt; B -&gt; C
              ^
              |
           HEAD
  </code></pre>
  
  <p>I want to create a new repository whose master branch begins at commit <code>C</code> (HEAD) of the current repository. </p>
  
  <pre><code>  C
    ^
    |
  HEAD
  </code></pre>
  
  <p>Additionally, if a new commit <code>D</code> is added to the current repository:</p>
  
  <pre><code>  A -&gt; B -&gt; C -&gt; D
                   ^
                   |
                  HEAD
  </code></pre>
  
  <p>The new repository will become:</p>
  
  <pre><code>  C -&gt; D
         ^
         |
        HEAD
  </code></pre>
  
  <p>On the next push/mirror. </p>
  
  <p>Due to learning to develop software while I committed changes to the project, the repository has gone in size due to large files being added and removed through it's long history (500 commits).</p>
  
  <p>Can this workflow be easily achieved in git? (Using both GitHub and GitLab)</p>