Ignore empty diffs.

git-svn-id: http://redmine.rubyforge.org/svn/trunk@1014 e93f8b46-1217-0410-a6f0-8f06a7374b81

lib/redmine/scm/adapters/abstract_adapter.rb

@@ -237,7 +237,8 @@ module Redmine
                 end
                 a = diff_table.add_line line
             end
-            self << diff_table
+            self << diff_table unless diff_table.empty?
+            self
         end
       end