title: All dependencies are not downloaded with "pip download"
body: <p>I'm trying to setup a local directory with packages that can be reused for installation on a machine without an internet connection but I'm having problems with some of the packages.</p>
  
  <p>I first download the packages with  </p>
  
  <pre><code>pip download -r requirements.txt -d my_packages --no-binary :all:
  </code></pre>
  
  <p>And then I try to install them with</p>
  
  <pre><code>pip install -r requirements.txt --no-index -f my_packages
  </code></pre>
  
  <p>One of the packages I'm having trouble installing is <code>elasticsearch-dsl==6.1.0</code>:</p>
  
  <pre><code>pip install -r requirements --no-index -f my_packages
  Looking in links: my_packages
  Collecting elasticsearch-dsl==6.1.0
  Collecting six (from elasticsearch-dsl==6.1.0)
  Collecting python-dateutil (from elasticsearch-dsl==6.1.0)
    Installing build dependencies ... error
    Complete output from command /Users/Oskar/.pyenv/versions/2.7.15/envs/no_internet/bin/python2.7 -m pip install --ignore-installed --no-user --prefix /private/var/folders/36/t0_t6_td2f560t2j0149vjmw0000gn/T/pip-build-env-moib0N --no-warn-script-location --no-binary :none: --only-binary :none: --no-index --find-links my_packages -- setuptools wheel:
    Looking in links: my_packages
    Collecting setuptools
      Could not find a version that satisfies the requirement setuptools (from versions: )
    No matching distribution found for setuptools
  </code></pre>
  
  <p>Sure, <code>setuptools</code> I can manually install but there is more packages than that which is required for all the other packages. <code>django-guardian==1.4.9</code> is another example which requires <code>pytest-runner</code> which for some reason is not downloaded with <code>pip download</code></p>