fix passing exit status from shell provision to packer

[ranl]

when a shell provision returns with an exit code > 0 packer should fail the build.
from some reason /bin/bash shell of OpenSSH always return exit code 0 which could hide the fact that the provision failed..

this commit will configure the passwd to use the /bin/sh shell which returns the exit code as expected

Note: I didn't test this with vagrant

[joefitzgerald]

@ranl @sneal Have you had a chance to test if this works as expected with Vagrant?

[ranl]

@joefitzgerald I don't use Vagrant so I didn't test it... =/
I think that as long as you execute your commands under cmd /c it should work fine

[joefitzgerald]

So... When using Vagrant, the reality is that you should really be using WinRM / vagrant-windows - rendering this concern moot. I'm inclined to merge this. @sneal @dylanmei do you agree or have objections?

[dylanmei]

I'm not in a position to test this this weekend, but the develop builds can have final say. I believe the change should be good for all of us. Not worried about Vagrant either.

[joefitzgerald]

develop build passed, I'm releasing this.