Apache Mesos is now a Top-Level Apache project, and we've moved the codebase. The downloads page explains the essential information, but here's the scoop:

Please check out the source code from Apache's git repostory:

git clone https://git-wip-us.apache.org/repos/asf/mesos.git

or if you prefer GitHub, use the GitHub mirror:

git clone git://github.com/apache/mesos.git

For issue tracking and patches, we use Apache-maintained infrastructure including the JIRA issue tracker instead of the GitHub one, and review board for patches instead of pull requests.

Other information including documentation and a getting started guide are available on the Mesos website: http://mesos.apache.org

Thanks!

-- The Mesos developers