some more refactoring

lib/gitlab/import_export/project_tree_restorer.rb

@@ -62,21 +62,6 @@ module Gitlab
             relation_hash_list = @tree_hash[relation_key.to_s]
             save_relation_hash(relation_hash_list, relation_key)
           end
-
-
-          # relation_key = relation.is_a?(Hash) ? relation.keys.first : relation
-          # relation_hash_list = @tree_hash[relation_key.to_s]
-          #
-          # next unless relation_hash_list
-          #
-          # if relation_hash_list.is_a?(Array)
-          #   [relation_hash_list].flatten.each_slice(15) do |relation_hash_batch|
-          #     save_relation_hash(relation_hash_batch, relation_key, saved)
-          #   end
-          # else
-          #   save_relation_hash(relation_hash_list, relation_key, saved)
-          # end
-
         end
         @saved.all?
       end
@@ -123,6 +108,7 @@ module Gitlab
         tree_array = [tree_hash[relation_key]].flatten
 
         while relation_item = tree_array.shift
+          Project.transaction do
             process_sub_relation(relation, relation_item)
 
             if save
@@ -130,6 +116,7 @@ module Gitlab
               tree_hash[relation_key].delete(relation_item)
             end
           end
+        end
 
         tree_hash.delete(relation_key) if save
       end

lib/gitlab/import_export/shared.rb

@@ -16,7 +16,7 @@ module Gitlab
         error_out(error.message, caller[0].dup)
         @errors << error.message
         # Debug:
-        Rails.logger.error(error.backtrace)
+        Rails.logger.error(error.backtrace.join("\n"))
       end
 
       private