su: must be run from a terminal

[kvivek1115]

Version:

3.3.6 or latest master

Environment:

Vagrant Ubuntu 18.04

Scenario:

In order to perform knife bootstrap with a different root password to the authenticated user chef/chef#10181
it required to hit su - USER command

Steps to Reproduce:

require 'train'
train = Train.create('ssh', host: 'node1.test', port: 22, user: 'vagrant', key_files: './.vagrant/machines/default/virtualbox/private_key')

conn = train.connection
res = conn.run_command('su - root')

puts "STDOUT: #{res.stdout}"
puts "STDERR: #{res.stderr}"

>
STDOUT:
STDERR: su: must be run from a terminal

Expected Result:

it should at least open the new session for suing user.

Actual Result:

Raises an error STDERR: su: must be run from a terminal