title: use git repo url to check whether repository exists
body: <p>I have searched in google, they say "git ls-remote git-url" can say whether git repo exists or not.</p>
  
  <p>But i have a problem when use this command to check github unexisting https git url.</p>
  
  <p>for example, when I run below command, it will require input username and password.</p>
  
  <pre><code>$ git ls-remote https://github.com/grant/noexisted.git
  </code></pre>
  
  <p>I only want to check whether the repo exists or not, and I call "git ls-remote" command in
  ruby code, so how to skip this auto shell prompt?</p>