title: Python Dependency satisfied but pip still complains for zope.interface==4.6.0
body: <p>While installing all the packages, I am getting no matching version error for <code>zope.interface</code> package even though the version is present in the list.</p>
  <blockquote>
  <p>ERROR: Could not find a version that satisfies the requirement zope.interface==4.6.0 (from versions: 3.3.0b1, 3.3.0b2, 3.3.0, 3.3.0.1, 3.4.0b1, 3.4.0, 3.4.1, 3.5.0, 3.5.1, 3.5.2, 3.5.3, 3.6.0, 3.6.1, 3.6.2, 3.6.3, 3.6.4, 3.6.5, 3.6.6, 3.6.7, 3.6.8, 3.7.0, 3.8.0, 4.0.0, 4.0.1, 4.0.2, 4.0.3, 4.0.4, 4.0.5, 4.1.0, 4.1.1, 4.1.2, 4.1.3, 4.2.0, 4.3.0, 4.3.1, 4.3.2, 4.3.3, 4.4.0, 4.4.1, 4.4.2, 4.4.3, 4.5.0, 4.6.0, 4.7.0, 4.7.1, 4.7.2, 5.0.0, 5.0.1, 5.0.2, 5.1.0, 5.1.1, 5.1.2, 5.2.0, 5.3.0a1, 5.3.0, 5.4.0).<br />
  ERROR: No matching distribution found for zope.interface==4.6.0</p>
  </blockquote>
  <p>As seen above the version <em>to-be-installed</em> is present in the <em>from-versions</em> list but pip still complains and errors out.<br />
  What is going wrong here ?<br />
  I am on Python 3.9.5 with pip 21.1.1</p>