title: ERROR: gcloud crashed (AttributeError): 'Thread' object has no attribute 'isAlive'
body: <p>The problem occurs with macOs when trying to connect to VM through iap. The same command works from another system with the same credentials, so must be something to do with my local environment.</p>
  <p>This is the command I'm trying to run:</p>
  <pre><code>gcloud compute ssh **** --project=**** --zone=europe-west4-a --tunnel-through-iap
  </code></pre>
  <p>And it fails with this error:</p>
  <pre><code>ERROR: gcloud crashed (AttributeError): 'Thread' object has no attribute 'isAlive'
  
  If you would like to report this issue, please run the following command:
    gcloud feedback
  
  To check gcloud for common problems, please run the following command:
    gcloud info --run-diagnostics
  kex_exchange_identification: Connection closed by remote host
  ERROR: (gcloud.compute.ssh) [/usr/bin/ssh] exited with return code [255].
  </code></pre>
  <p>Google gives me no answer whatsoever</p>