title: Create patch or diff file from git repository and apply it to another different git repository
body: <p>I work on WordPress based project and I want to patch my project at each new release version of WP. For this, I want generate a patch between two commits or tags.</p>
  <p>For example, in my repo <code>/www/WP</code> I do this:</p>
  <pre class="lang-sh prettyprint-override"><code>$ git patch-format com1..com2 --stdout &gt; '~/patchs/mypatch.patch'
  
  # or
  
  $ git patch-format tag1..tag2 --stdout &gt; '~/patchs/mypatch.patch'
  </code></pre>
  <p><code>/www/WP</code> git natif WordPress</p>
  <p><code>/www/myproject</code> My git project WordPress based</p>
  <p>The <code>git apply</code> command line doesn't work, I think because we are in different repositories.</p>
  <p>Can I generate a patch file without a commit, just a differential and apply it to another git repository?</p>
  <p>Thank you.</p>