title: How are transitive dependencies installed in pip?
body: <p>I have two packages packageA and packageB. packageA depends on packageB. </p>
  
  <p>B has an unmodeled dependency on requests. I discovered this setting up a new environment. I modified the requirements file in /project/packageA of packageB so that it had a direct dependency on requests. Then I ran </p>
  
  <pre><code>cd /project/packageA
  pip install -e /project/packageB
  pip install -r requirements.txt
  </code></pre>
  
  <p>My intuition was that should have installed requests. However, in order to install requests I had to directly add it to /project/packageA/requirements.txt</p>
  
  <p>What's the right way to test this?</p>