title: Merge two PO files and overwrite matching translation rules
body: <p>I'm attempting to merge two PO files. </p>
  
  <p>I have a <code>base.po</code> file that has general translations.</p>
  
  <p>I have an <code>extra.po</code> which has extra translations that I'd like to add to the base file OR overwrite translations for if there are matching translation IDs. </p>
  
  <p>I've tried using <code>msgmerge</code>:</p>
  
  <pre><code>$ msgmerge extra.po base.po -o merge.po
  </code></pre>
  
  <p>But this comments out any translations with matching IDs. </p>
  
  <p>Looking at the <a href="https://www.gnu.org/software/gettext/manual/html_node/msgmerge-Invocation.html" rel="nofollow"><code>msgmerge</code> documentation</a>, it doesn't look like there is any option to effect this behavior.</p>
  
  <p>I'd like to be able to have multiple extra translation files (<code>extra1.po</code>, <code>extra2.po</code>, etc.) so I can merge them with the base translation file and use them in different contexts.</p>
  
  <p>Does anyone know how to do what I'm attempting?</p>