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:https://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