symfony/symfony — pull request #2382 by mvrhov (2011-10-11 19:50:37+00:00)
Title: session data needs to be encoded because it can contain non binary safe characters e.g null. 

Bug fix: yes
Feature addition: no
Backwards compatibility break: yes
Symfony2 tests pass: yes
Fixes the following tickets: #2067

I'm marking this as a compatibility break because session table should be cleared and even if not cleared all currently logged in users will be logged out.