CLI 400 error deploying to Google App Engine
<p>Today I got a new error when trying to deploy my application to Google App Engine via the command line:</p>

<pre><code>Updating module [default]...-ERROR: (gcloud.preview.app.deploy) Server responded with code [400]:
  Bad Request Unexpected HTTP status 400.
  Your app may not have more than 120 versions.
  Please delete one of the existing versions before trying to create a new version.
</code></pre>

<p>I am deploying to the top level using <code>--promote</code>, not creating other versions. How do I fix this error?</p>