title: Packer amazon-ebs : AuthFailure
body: <p>For some reason Packer fails to authenticate to AWS, using plain aws client works though, and my environment variables are correctly set:</p>
  
  <pre><code>AWS_ROLE_SESSION_NAME=...
  AWS_SESSION_TOKEN=...
  AWS_SECRET_ACCESS_KEY=...
  AWS_ROLE=...
  AWS_ACCESS_KEY_ID=...
  AWS_CLI=...
  AWS_ACCOUNT=...
  AWS_SECURITY_TOKEN=...
  </code></pre>
  
  <p>I am using authentication using aws saml, and Packer gives me the following: </p>
  
  <pre><code>Error querying AMI: AWS was not able to validate the provided access credentials (AuthFailure)
  </code></pre>