title: RuntimeError: Click will abort further execution because Python 3 was configured to use ASCII as encoding for the environment
body: <p>I tried to deploy my flask application in a docker in ubuntu18.04, and I was using python3.5 in my pipenv. But when I run <code>docker build -t flask .</code>, at a step of <code>RUN pipenv install</code>,I got this error:</p>
  
  <pre><code>RuntimeError: Click will abort further execution because Python 3 was configured to use ASCII as encoding for the environment. Consult https://click.palletsprojects.com/en/7.x/python3/ for mitigation steps.
  
  This system supports the C.UTF-8 locale which is recommended.
  You might be able to resolve your issue by exporting the
  following environment variables:
  
      export LC_ALL=C.UTF-8
      export LANG=C.UTF-8
  
  </code></pre>
  
  <p>But when I checked my locale with <code>locale</code>,it returned</p>
  
  <pre><code>LANG=C.UTF-8
  LANGUAGE=
  LC_CTYPE="C.UTF-8"
  LC_NUMERIC="C.UTF-8"
  LC_TIME="C.UTF-8"
  LC_COLLATE="C.UTF-8"
  LC_MONETARY="C.UTF-8"
  LC_MESSAGES="C.UTF-8"
  LC_PAPER="C.UTF-8"
  LC_NAME="C.UTF-8"
  LC_ADDRESS="C.UTF-8"
  LC_TELEPHONE="C.UTF-8"
  LC_MEASUREMENT="C.UTF-8"
  LC_IDENTIFICATION="C.UTF-8"
  LC_ALL=C.UTF-8
  
  </code></pre>
  
  <p>I guessed maybe something was different in docker so I tried to add</p>
  
  <pre><code>RUN export LC_ALL=C.UTF-8
  RUN export LANG=C.UTF-8
  </code></pre>
  
  <p>into my Dockerfile, but still got this error. </p>
  
  <p>I'm shriveled. Since I had set all to C.utf-8, I have no idea why it's still complaining. I had searched this problem online but unfortunately all the methods seemed to be useless in my case :( 
  Maybe there are some tiny things I have been ignoring, but I really cannot figure them out. I hope someone could help me out and save me another 3 hours.Thanks.</p>