Correct puppet module list check in beaker

The final check during the prep stage, where `puppet module list` is
run so that its output can be used for debugging, should run on the
current host in the loop, not the first host in the array.

Change-Id: I78d5d616fbed44c21005e35e78f5d54371570b6b

spec/spec_helper_acceptance.rb

@@ -39,7 +39,7 @@ RSpec.configure do |c|
       # Install the module being tested
       puppet_module_install(:source => proj_root, :module_name => 'swift')
       # List modules installed to help with debugging
-      on hosts[0], puppet('module','list'), { :acceptable_exit_codes => 0 }
+      on host, puppet('module','list'), { :acceptable_exit_codes => 0 }
     end
   end
 end