title: What does --config-env=http.extraheader=env_var_http.extraheader mean when passed to git inside Azure Pipelines build run?
body: <p>The full command like could be something like this:</p>
  <pre><code>git --config-env=http.extraheader=env_var_http.extraheader fetch --force --tags --prune --prune-tags --progress --no-recurse-submodules origin
  </code></pre>
  <p>I have a feeling it has to do with authenticating git command to the git server, but I do not understand how does it work.</p>