fix passing exit status from shell provisioner to packer

scripts/openssh.ps1

@@ -32,6 +32,11 @@ Write-Host "Setting SSH home directories"
     Foreach-Object { $_ -replace '/home/(\w+)', '/cygdrive/c/Users/$1' } |
     Set-Content 'C:\Program Files\OpenSSH\etc\passwd'
 
+# Set shell to /bin/sh to return exit status
+$passwd_file = Get-Content 'C:\Program Files\OpenSSH\etc\passwd'
+$passwd_file = $passwd_file -replace '/bin/bash', '/bin/sh'
+Set-Content 'C:\Program Files\OpenSSH\etc\passwd' $passwd_file
+
 # fix opensshd to not be strict
 Write-Host "Setting OpenSSH to be non-strict"
 $sshd_config = Get-Content "C:\Program Files\OpenSSH\etc\sshd_config"
@@ -74,4 +79,4 @@ netsh advfirewall firewall add rule name="ssh" dir=in action=allow protocol=TCP
 
 if ($AutoStart -eq $true) {
     Start-Service "OpenSSHd"
-}
\ No newline at end of file
+}