Cleanup rake task for public/private champ outage

lib/tasks/2018_02_14_clean_double_champ_private.rake

@@ -0,0 +1,14 @@
+namespace :'2018_02_14_clean_double_champ_private' do
+  task clean: :environment do
+    Champ.where(private: true).group_by(&:dossier_id).each_value do |champs|
+      seen = []
+      champs.each do |champ|
+        if champ.type_de_champ_id.in?(seen)
+          champ.destroy
+        else
+          seen << champ.type_de_champ_id
+        end
+      end
+    end
+  end
+end