title: Added files not found during execution
body: <p>I have a <code>MyApp.spec</code> files where I have:</p>
  <pre><code>a = Analysis(...
  datas=[
         ('file_1.jpg', '.', 
         ('file_2.mplstyle', '.'),
        ]
  ...)
  </code></pre>
  <p>In my code, these files are used in methods as, for example, <code>plt.style.use('file_2.mplstyle')</code> (python files and such extra files are in the same folder).</p>
  <p>I compile my code with <code>pyinstaller --onefile MyApp.spec</code> and it yields no error.</p>
  <p>However, at execution time, the <code>file_2.mplstyle</code> is not found.</p>
  <p>So far, the only trick for the execution to succeed is to manually copy both files to the <code>dist/</code> directory.</p>