"ssh -t -t " expected, but config option "tty" seems to do nothing.

gistfile1.txt

https://docs.saltstack.com/en/latest/ref/clouds/all/salt.cloud.clouds.vsphere.html

code
====
 --> /usr/lib/python2.7/dist-packages/salt/utils/cloud.py (starting from line 2019)
...
    if tty:
        # Use double `-t` on the `ssh` command, it's necessary when `sudo` has
        # `requiretty` enforced.
        ssh_args.extend(['-t', '-t'])
...


my config
=========
vsphere-ubuntu16:
  provider: vsphere-vc1
  image: ubuntu1604
  folder: saltstack
  resourcepool: resgroup-411
  minion:
    master: salt.*domain*.de
  template_user: salt
  template_password: salt
  sudo: True
  sudo_password: salt
  tty: True

but ssh option "-t" will not be added to salt-cloud, as expected. (config option tty: True)
  
# salt-cloud -p vsphere-ubuntu16 myminion --keep-tmp -l all
...
Do 17. Mär 15:19:37 CET 2016
[DEBUG   ] Do 17. Mär 15:19:37 CET 2016
[DEBUG   ] Logging into 10.206.9.45:22 as salt
[DEBUG   ] Using sudo to run command sudo -S "XXX-REDACTED-XXX" test -e '/tmp/.saltcloud-4f999f4d-7ff1-48f7-bfd3-a9c0cf8d65f0'
[DEBUG   ] SSH command: 'ssh -oStrictHostKeyChecking=no -oUserKnownHostsFile=/dev/null -oControlPath=none -p 22 salt@10.206.9.45 sudo -S "XXX-REDACTED-XXX" test -e \'/tmp/.saltcloud-4f999f4d-7ff1-48f7-bfd3-a9c0cf8d65f0\''

So whats wrong??