WIP: preserve Issue #479 changes

backend/app/controllers/posts_controller.rb

@@ -429,7 +429,7 @@ class PostsController < ApplicationController
     filters = literals.map do |literal|
       internal, = source_ids.fetch(literal[:name])
       name = internal.empty? ? literal[:name] : names[internal.first]
-      return head :unprocessable_entity unless name && internal.length <= 1
+      return head :unprocessable_content unless name && internal.length <= 1
 
       literal[:negative] ? "not:#{ name }" : name
     end
@@ -438,7 +438,7 @@ class PostsController < ApplicationController
     literals.zip(translated).each do |literal, translation|
       unless (source_ids.fetch(literal[:name]).map(&:sort) ==
           target_ids.fetch(translation[:name]).map(&:sort))
-        return head :unprocessable_entity
+        return head :unprocessable_content
       end
     end
     index = 0