Server error messages which contain special chars aren't correctly displayed

If a server error message contains special characters like '%' the prepared statement error function tries to substitute these characters which ends up in truncated error messages.

Example:
show grants for mysqltest_8

Error sent from server:
There is no such grant defined for user 'mysqltest_8' on host '%'

Error displayed by client:
There is no such grant defined for user 'mysqltest_8' on host '