symfony/MonologBundle — pull request #109 by stephpy (2014-12-24 14:46:51+00:00)
Title: Set SwiftMailer creation message as lazy.

At this moment, with a config:

```
swift:
type: swift_mailer
from_email: user@domain.tld
to_email: user@domain.tld
level: debug
```

A `Swift_Message` instance is created for any place where `logger` is injected. Everybody know the cost of a `Swift_Message` instance ...