Fix #3272: Unicode tags are still being allowed.

* Don't allow adding tags with invalid names when they already exist in
  the tags table.
* If an invalid tag is added, show an warning and ignore the tag instead
  of failing with a hard error.
* Move the _(cosplay) tag validation into the tag name validator.

app/logical/tag_name_validator.rb

@@ -17,14 +17,21 @@ class TagNameValidator < ActiveModel::EachValidator
       record.errors[attribute] << "'#{value}' cannot end with an underscore"
     when /__/
       record.errors[attribute] << "'#{value}' cannot contain consecutive underscores"
-    when /[^[[:graph:]]]/
+    when /[^[:graph:]]/
       record.errors[attribute] << "'#{value}' cannot contain non-printable characters"
-    when /[^[[:ascii:]]]/
+    when /[^[:ascii:]]/
       record.errors[attribute] << "'#{value}' must consist of only ASCII characters"
     when /\A(#{Tag::METATAGS.join("|")}):(.+)\z/i
       record.errors[attribute] << "'#{value}' cannot begin with '#{$1}:'"
     when /\A(#{Tag.categories.regexp}):(.+)\z/i
       record.errors[attribute] << "'#{value}' cannot begin with '#{$1}:'"
+    when /\A(.+)_\(cosplay\)\z/i
+      tag_name = TagAlias.to_aliased([$1]).first
+      tag = Tag.find_by_name(tag_name)
+
+      if tag.present? && tag.category != Tag.categories.character
+        record.errors[attribute] << "#{tag_name} must be a character tag"
+      end
     end
   end
 end