https://github.com/Seldaek/monolog/blob/master/CHANGELOG.mdown#1120-2014-12-29
Notable changes:
- Break: HandlerInterface::isHandling now receives a partial record containing only a level key. This was always the intent and does not break any Monolog handler but is strictly speaking a BC break and you should check if you relied on any other field in your own handlers.
- SamplingHandler was added
- @csteipp's security issue was patched