title: Pip freeze generating '@ file:///' on conda environment
body: <p>First time this is happening to me, and I have no idea why pip is outputting the requirements in such strange form. I'm using a conda environment. Output example from <code>pip freeze</code>:</p>
  <pre><code>aioredis @ file:///home/conda/feedstock_root/build_artifacts/aioredis_1591809643295/work
  amqp @ file:///home/conda/feedstock_root/build_artifacts/amqp_1591005859311/work
  asgiref==3.2.7
  async-timeout==3.0.1
  attrs==19.3.0
  </code></pre>
  <p>Why aren't <code>aioredis</code> and <code>amqp</code> listed with their respective version just like the other requirements?</p>