title: '=' is not a valid operator when trying to install packages with pip
body: <p>I am trying to install some packages from a .txt file. When I try to install them, <code>pip</code> is reading the file but is saying that <code>'=' is an invalid operator</code>. I have also tried changing the <code>'='</code> to <code>'=='</code> with no success.</p>
  <p>For example, I am trying to install <code>aniso8601=8.0.0=py_0</code>, but keep getting the error:</p>
  <pre><code>ERROR: Invalid requirement: 'aniso8601=8.0.0=py_0' (from line 4 of requirements.txt)
  Hint: = is not a valid operator. Did you mean == ?
  </code></pre>
  <blockquote>
  <p>Edit: I was getting the list of dependencies from someone else and the py_0 portion was an oversight by me as it was something added that they left on the end of their list.</p>
  </blockquote>