Temporary field wasn't restored to default values after ON DUPLICATE KEY
 UPDATE event, which results in wrong data being inserted in new record.


sql/sql_insert.cc:
  Fix bug #10886 - INSERT ... SELECT ... ON DUPLICATE KEY UPDATE produces bad results
mysql-test/t/insert_select.test:
  Test case for bug #10886 - INSERT ... SELECT ... ON DUPLICATE KEY 
  UPDATE produces bad results
mysql-test/r/insert_select.result:
  Test case for bug #10886 - INSERT ... SELECT ... ON DUPLICATE KEY UPDATE 
  produces bad results