title: Gerrit error when Change-Id in commit messages are missing
body: <p>I set up a branch in the remote repository and made some commits on that branch.
  Now I want to merge the remote branch to the remote master.</p>
  
  <p>Basically follows are my operations:</p>
  
  <ol>
  <li>checkout branch</li>
  <li>checkout master</li>
  <li>merge branch and fix merging errors</li>
  <li>commit</li>
  <li>push origin HEAD:refs/for/master</li>
  </ol>
  
  <p>But get error messages on the 5th step:</p>
  
  <pre><code>remote: Resolving deltas:   0% (0/12)
  
  remote: ERROR: missing Change-Id in commit message
  ...
  
  remote: Change-Id: I55862204ef71f69bc88c79fe2259f7cb8365699a
  
  To ssh://prc@test.gerrit.xxx.com:29418/hello_git
   ! [remote rejected] HEAD -&gt; refs/for/master (missing Change-Id in commit message)
  </code></pre>