title: Missing distribution spec error using pip install from requirements
body: <p>I have just created a fresh virtualenv into which I want to run my <code>pip install</code>. However, I'm getting this error:</p>
  
  <pre><code>raise ValueError("Missing distribution spec", line)
  ValueError: ('Missing distribution spec', '/path/to/dir/requirements.txt')
  </code></pre>
  
  <p>My <strong>requirements.txt</strong>:</p>
  
  <pre><code>Django==1.3
  Jinja2==2.6
  MySQL-python==1.2.3
  PIL==1.1.7
  Pygments==1.5
  Sphinx==1.1.3
  Werkzeug==0.8.3
  django-debug-toolbar==0.9.4
  django-excel-response==1.0
  django-extensions==0.8
  docutils==0.9.1
  ipython==0.12
  wsgiref==0.1.2
  </code></pre>
  
  <p>What is going wrong?</p>