title: Bumped version on git private repo and now install requirements fail
body: <p>I have access to a git repo that implements a dependency that I'm using in my project. Naturally, this dependency is in my requirements.txt like this: </p>
  
  <pre><code>git+https://HASH@github.com/repowner/dependency_name.git@v0.1.4
  </code></pre>
  
  <p>It always worked fine, but recently I needed to make some changes in the dependency, so I opened a pull request and got it reviewed by my teacher (repo owner) before merging it. In this PR I also bumped the version, and did just like a previous PR(from another author). All I changed was a changelog file that is pure text and the <code>setup.py</code>:</p>
  
  <p><strong>setup.py</strong></p>
  
  <pre><code>from setuptools import setup, find_packages
  
  setup(
      name="dependency_name",
      version='0.1.5', #&lt;&lt;&lt; Only changed this from 0.1.4 to 0.1.5
      description="Desc",
      license='...',
      platforms=['OS Independent'],
      keywords='...',
      author='...',
      url="https://github.com/repoowner/dependency_name",
      packages=find_packages()
  )
  </code></pre>
  
  <p>I assumed this was enough (as it was done like this before). I've updated my <code>requirements.txt</code> to:</p>
  
  <pre><code>git+https://HASH@github.com/repowner/dependency_name.git@v0.1.5  
  </code></pre>
  
  <p>But now, when I try to <code>pip install -r requirements.txt</code> I get:</p>
  
  <pre><code>Collecting git+https://****@github.com/repoowner/dependency_name.git@v0.1.5 (from -r requirements.txt (line 3))
    Cloning https://****@github.com/repoowner/dependency_name.git (to revision v0.1.5) to /tmp/pip-req-build-fvq5k_04
    Running command git clone -q 'https://****@github.com/repoowner/dependency_name.git' /tmp/pip-req-build-fvq5k_04
    WARNING: Did not find branch or tag 'v0.1.5', assuming revision or ref.
    Running command git checkout -q v0.1.5
    error: pathspec 'v0.1.5' did not match any file(s) known to git
  ERROR: Command errored out with exit status 1: git checkout -q v0.1.5 Check the logs for full command output.
  </code></pre>
  
  <p>Did I missed something when trying to bump the version?</p>
  
  <p>BTW: If I try the 0.1.4 it installs without my recent changes.</p>