* roy huang:

>   Another problem  ,I can't  update branch_2_1_x from  svn these
>   few  days,always said  src/block/ajax already  exits(something
>   like that)

Remove the whole working directory and checkout again.  Subversion
is unable to catchup with the lots of changes in svn:externals.
-- 
Jean-Baptiste Quenot
http://caraldi.com/jbq/