title: git submodule update is stuck on "Cloning into ..." on remote VPS - Ubuntu 18.04
body: <p>I'm trying to run <code>git submodule update</code> command on my ubuntu machine but it hangs on <code>Cloning into '/home/ubuntu/mazerat/mazerat/tasks/instabotpy'...</code></p>
  
  <p>I checked following solutions but doesn't work.</p>
  
  <blockquote>
    <p><a href="https://stackoverflow.com/questions/39765663/git-submodule-init-does-absolutely-nothing/39766926">git submodule init does absolutely nothing </a></p>
    
    <p><a href="https://teamcity-support.jetbrains.com/hc/en-us/community/posts/206867175-Git-submodules-update-is-stuck" rel="nofollow noreferrer">Git submodules update is stuck 
    </a></p>
  </blockquote>
  
  <p>Same instance works properly on macOS Mojave (Version 10.14.3) and Windows 10.</p>
  
  <p>Also machine SSH public key is set on github.</p>
  
  <p>I tried to run command as root (after set the root ssh key) for premission check but didn't matter.</p>
  
  <p><strong><em>.gitmodules</em></strong></p>
  
  <pre><code>[submodule "mazerat/tasks/instabotpy"]
      path = mazerat/tasks/instabotpy
      url = git@github.com:motameni/instabot.py.git
  </code></pre>