Fix stdIn hanging issue

[twhiston]

I had an issue with Semaphore where trying to connect to a host that is not already in the known hosts list would ask you if you wished to add them to the known_hosts. This would cause semaphore to be unable to start any other task and a restart would be needed.
With this fix I simply attach a blank string as stdin to the playbook run command, which causes the host key verification to fail in this instance

[twhiston]

@strangeman any thoughts on this?

[strangeman]

Interesting. I never had this issue, because we use ssh_args = -o StrictHostKeyChecking=no in our ansible.cfg.
Seems like a simple and effective solution.

[twhiston]

Thanks for the approval :)

Due to our security policy we cant set StrictHostKeyChecking=no on our Sempahore machine, so this really bites us if asking for a key hangs the whole program. I've been trying to think if just passing an empty string could ever cause any unintended side effects, but i've never experienced any so I think we can call this ready.