If during a FLUSH PRIVILEGES the server fails to load the new privilege
tables, the error message is lost. This patch is a back port from 5.1 which
adresses this issue by setting the server in an error state if a failure
occurrs.
  
This patch also corrects an incorrect variable assignment which might
cause an error state to be reverted by coincidence.

sql/sql_parse.cc:
  * Set error state if acl_reload or grant_reload fails.
  * Fix bad variable assignment which cancels previous error status.