title: Why does setuptools not understand git+https URLs?
body: <p>According to <a href="https://pythonhosted.org/setuptools/setuptools.html#dependencies-that-aren-t-in-pypi" rel="nofollow">Dependency section in the setuptools manual</a> <code>git</code> repository URLs can be specified in the <code>dependency_links</code> argument to <code>setup</code> with <code>git+URL</code>. Yet, </p>
  
  <pre><code>cd /tmp
  mkdir py-test
  cd py-test
  touch __init__.py
  </code></pre>
  
  <p>and creation of a <code>setup.py</code> file with </p>
  
  <pre><code>from setuptools import setup, find_packages
  from pkg_resources import parse_version
  
  setup(
      name = "py-test",
      version = "1.0",
      packages = ["."],
      dependency_links = [
          "git+https://github.com/wxWidgets/wxPython.git"
      ],
      install_requires = ["wxPython"],
  )
  </code></pre>
  
  <p>causes the error <code>Download error on git+https://github.com/wxWidgets/wxPython.git: unknown url type: git+https -- Some packages may not be found!</code> when I run <code>python setup.py build &amp;&amp; sudo setup.py install</code>.</p>
  
  <p>The installation of the package <code>python-setuptools-git</code> doesn't help.</p>
  
  <p>I'm using <code>setuptools</code> 18.2 with <code>python</code> 2.7 on Ubuntu 15.04.</p>