Homebrew/homebrew — pull request #33146 by utdrmac (2014-10-13 19:44:54+00:00)
Title: pt-toolkit. Remove force install of mysql.

MySQL is not required to be install on the same host to use percona-toolkit. It is 100% optional. Mike said to make it :recommended but even then, it is installed without user intervention. I chose to make it :optional so that if users want to install mysqld locally, they can --with-mysql or install it with brew outside this package.
-Matthew, Percona Consultant ;)