Every time a build is triggered, scm plugin retrieves changes and stores them in changelog.

1. If you create a build that is executed on every newest commit, for tag "tip". Scm plugin retrieves a huge list of all commits, the list should be limited to current branch and maybe 20 latest commits, but not hundreds like it does now.
2. If the build fails, all of the users that where in those commits get notified, but only the last commiter should be notified as he broke the build.