Resolve aliases when removing negated tags (fix #2730).

app/models/post.rb

@@ -614,6 +614,7 @@ class Post < ActiveRecord::Base
     def remove_negated_tags(tags)
       negated_tags, tags = tags.partition {|x| x =~ /\A-/i}
       negated_tags = negated_tags.map {|x| x[1..-1]}
+      negated_tags = TagAlias.to_aliased(negated_tags)
       return tags - negated_tags
     end
 

test/unit/post_test.rb

@@ -668,6 +668,13 @@ class PostTest < ActiveSupport::TestCase
           @post.reload
           assert_equal("aaa ccc", @post.tag_string)
         end
+
+        should "resolve aliases" do
+          FactoryGirl.create(:tag_alias, :antecedent_name => "/tr", :consequent_name => "translation_request")
+          @post.update(:tag_string => "aaa translation_request -/tr")
+
+          assert_equal("aaa", @post.tag_string)
+        end
       end
 
       should "have an array representation of its tags" do