Is there a bug/issue tracking system which integrates with Mercurial?

I've used Trac/Subversion before and really like the integration. My current project is using Mercurial for distributed development and it'd be nice to be able to track issues/bugs and have this be integrated with Mercurial. I realized this could be tricky with the nature of DVCS.

I'd also like to add Redmine to the list. I started with Trac, but I found the mercurial support (and the administrative interface for everything) to be much better in Redmine.