Fix the regression after changes in 23f4d94 which caused every kitchen test eventually fail when you provided a value for the interface configuration parameter.

The failure message is:

>>>>>> ------Exception-------
>>>>>> Class: Kitchen::ActionFailed
>>>>>> Message: Failed to complete #create action: [undefined method `public' for #<Fog::Compute::AWS::Server:0x000000041bc430>]
>>>>>> ----------------------
>>>>>> Please see .kitchen/logs/kitchen.log for more details
>>>>>> Also try running `kitchen diagnose --all` for configuration

See also:

23f4d94#diff-c5498dad76244656522b77033980c6a6R238

Author: Yusuke KUOKA

lib/kitchen/driver/ec2.rb

@@ -247,7 +247,7 @@ def hostname(server)
       #
       def self.hostname(server, interface_type=nil)
         if interface_type
-          INTERFACE_TYPES.fetch(interface_type) do
+          interface_type = INTERFACE_TYPES.fetch(interface_type) do
             raise Kitchen::UserError, "Invalid interface [#{interface_type}]"
           end
           server.send(interface_type)