title: systemd start service after another one stopped issue
body: <p>I have 2 services that i need to start.
  First service has download jobs required for second service.</p>
  
  <p>First service </p>
  
  <pre><code>[Unit]
  Description=First
  After=network.target
  </code></pre>
  
  <p>Second service</p>
  
  <pre><code>[Unit]
  Description=Second
  After=First
  </code></pre>
  
  <p>Problem is they both start at the same time, i need second service to wait until first one is dead. 
  I don't wait to use sleep because download jobs can be big.
  Thank you.</p>