The Darshan source code, issue tracking, and milestone management has been moved to the Darshan gitlab page at ANL. You can find instructions there for how to clone the repository.
If you have an existing clone of the old Darshan repository, then you can connect it to the new repository with the following command:
git remote set-url origin https://xgitlab.cels.anl.gov/darshan/darshan.git
If you are interested in contributing to Darshan, the gitlab page brings several new features to the project including the ability for external users to sign up for accounts, simplified forking and pull requests, and the ability to track issues and milestones.