title: Why isn't pip installing the latest version of a package, even when a newer version is on PyPI?
body: <p>I was trying to upgrade to the latest version of a package I had installed with <code>pip</code>, but for some reason it won't get the latest version. I've tried uninstalling the package in question, or even reinstalling <code>pip</code> entirely, but it still refuses to get the latest version from PyPI. When I try to pin the package version (e.g. <code>pip install package==0.10.0</code>) it says that it "Could not find a version that satisfies the requirement package==0.10.0 (from versions: ...)"</p>
  
  <p><code>pip search package</code> even acknowledges that the installed version isn't the latest, labeling the two versions for me.</p>
  
  <p>I've seen other questions with <a href="https://stackoverflow.com/q/21868684/3551604">external files</a> or <a href="https://stackoverflow.com/q/14617136/3551604">local versions</a>, but I've tried the respective solutions (<code>--allow-external</code> doesn't exist anymore, and <code>--no-cache-dir</code> doesn't help) and I'm still stuck on the older version.</p>