title: pip error while installing azure cli extension behind proxy
body: <p>could someone help me please:</p>
  
  <p>I am using Azure cli behind proxy and I have fiddler running.
  I am running following commands and setup to login into my azure account, </p>
  
  <pre><code>SET ADAL_PYTHON_NO_SSL_VERIFY=1
  SET AZURE_CLI_DISABLE_CONNECTION_VERIFICATION=1        
  az login --tenant &lt;company domain&gt;
  </code></pre>
  
  <p>It works well and gives me the list of subscriptions associated with my account.But,
  I need to install Azure-devops extension and when i run:</p>
  
  <pre><code>az extension add --name azure-devops
  </code></pre>
  
  <p>I am getting error: cli.azure.cli.core.util : An error occurred. Pip failed with status code 1.</p>
  
  <p>looking into fiddler it says:
  407 proxy authentication  error while connecting to on premise nexus.
  My pip config:</p>
  
  <pre><code>[list]
  format=columns
  [global]
  disable-pip-version-check = true
  trusted-host = nexusurl
  index = https://[username]:[userpassword]@&lt;nexusurl&gt;
  index-url = https://[username]:[userpassword]@&lt;nexusurl&gt;
  </code></pre>
  
  <p>i couldnt figure out what i am missing.</p>