branches/5.1:

Merge change from MySQL AB:

ChangeSet@1.2557, 2007-11-28 19:43:50+01:00, tnurnberg@mysql.com +21 -0
  Bug#31177: Server variables can't be set to their current values

  Default values of variables were not subject to upper/lower bounds
  and step, while setting variables was. Bounds and step are also
  applied to defaults now; defaults are corrected quietly, values
  given by the user are corrected, and a correction-warning is thrown
  as needed. Lastly, very large values could wrap around, starting
  from 0 again. They are bounded at the maximum value for the
  respective data-type now if no lower maximum is specified in the
  variable's definition.

  mysql-test/r/innodb.result@1.171, 2007-11-28 19:43:48+01:00, tnurnberg@mysql.com +4 -0
    We throw a warning now when we adjust out of range parameters.

mysql-test/innodb.result

@@ -1768,6 +1768,8 @@ show variables like "innodb_thread_concurrency";
 Variable_name	Value
 innodb_thread_concurrency	8
 set global innodb_thread_concurrency=1001;
+Warnings:
+Warning	1292	Truncated incorrect innodb_thread_concurrency value: '1001'
 show variables like "innodb_thread_concurrency";
 Variable_name	Value
 innodb_thread_concurrency	1000
@@ -1787,6 +1789,8 @@ show variables like "innodb_concurrency_tickets";
 Variable_name	Value
 innodb_concurrency_tickets	1000
 set global innodb_concurrency_tickets=0;
+Warnings:
+Warning	1292	Truncated incorrect innodb_concurrency_tickets value: '0'
 show variables like "innodb_concurrency_tickets";
 Variable_name	Value
 innodb_concurrency_tickets	1