do
local std_merge3_from_merge_changelog = merge3
function merge3 (anc_path, left_path, right_path, merged_path, ancestor, left, right) 
   if merged_path == "ChangeLog" then
      local ret
      local lfile = write_to_temporary_file (left) 
      local afile =   write_to_temporary_file (ancestor) 
      local rfile =   write_to_temporary_file (right) 
      local outfile = write_to_temporary_file ("") 
      local res = execute("merge.ChangeLog", afile, lfile, rfile, outfile)
      if res == 0 then
         ret = read_contents_of_file (outfile, "r") 
         if string.len(ret) then
            return ret
         end
      end
   end
   return std_merge3_from_merge_changelog(anc_path, left_path, right_path, merged_path, ancestor, left, right)
end
end