Comment 1 for bug 1188585

It already says at the beginning:

"This feature is intended to provide a general mechanism (using log_warnings_silence) to disable certain warning messages to the log file."

but it should also explicitly say that it does not influence warnings client gets as a result of "unsafe" statement execution.

Same applies to pages for other versions:

http://www.percona.com/doc/percona-server/5.1/flexibility/log_warnings_suppress.html
http://www.percona.com/doc/percona-server/5.6/flexibility/log_warnings_suppress.html