[GH-195] Add failing test to demonstrate parse error when @ is present in the description

This issue is created automatically through a Github pull request on behalf of Seldaek:

Url: https://github.com/doctrine/common/pull/195

Message:

If someone can take this and fix the issue it'd be great. I couldn't figure it out at a quick glance and I don't really have time, but it's a pretty messed up bug and not so trivial to debug if you don't know what happens in the background so I'd say it's pretty important.