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
BugTracker.NET now supports Mercurial integration in the same way it supports Subversion and git. BugTracker.NET is a free, open source, ASP.NET bug tracking system.
Other free, open source bug trackers that support Mercurial: