Wrong filters are applied when exporting issues to CSV with blank filter (#23206).

Patch by Go MAEDA.

git-svn-id: http://svn.redmine.org/redmine/trunk@15608 e93f8b46-1217-0410-a6f0-8f06a7374b81

app/helpers/queries_helper.rb

@@ -257,6 +257,8 @@ module QueriesHelper
           tags << hidden_field_tag("v[#{field}][]", value, :id => nil)
         end
       end
+    else
+      tags << hidden_field_tag("f[]", "", :id => nil)
     end
     if query.column_names.present?
       query.column_names.each do |name|