fix rubocop issues

source/lib/vagrant-openstack-provider/config.rb

@@ -177,15 +177,17 @@ def merge(other)
 
         # Set all of our instance variables on the new class
         [self, other].each do |obj|
+          # rubocop:disable Style/Next
           obj.instance_variables.each do |key|
+            # rubocop:enable Style/Next
             # Ignore keys that start with a double underscore. This allows
             # configuration classes to still hold around internal state
             # that isn't propagated.
-            if !key.to_s.start_with?("@__")
+            unless key.to_s.start_with?('@__')
               # Don't set the value if it is the unset value, either.
               value = obj.instance_variable_get(key)
               if [:@networks, :@volumes, :@rsync_includes].include? key
-                result.instance_variable_set(key, value) if !value.empty?
+                result.instance_variable_set(key, value) unless value.empty?
               else
                 result.instance_variable_set(key, value) if value != UNSET_VALUE
               end