When all else fails, it is important to be able to search within github and have forks point to the main repository for ongoing development, so as a last resort ROS forks of repos should be deleted and re-uploaded from a local clone.
As others outlined in this discussion, it is important to get in contact with the owners of repositories that no longer wish to maintain them and ask them to transfer their ownership within github for the reasons below.
Even if an owner adds notice to a repository regarding a new upstream fork, there is still an actual problem transferring repository ownership would fix. I found this conversation from my post in sniekum/ar_track_alvar/issues/124, so please look at the top of ros_perception/ar_track_alvar page. There is a message there:
forked from
sniekum/ar_track_alvar
Every single fork points to the owner’s repository, which is inconvenient, but there is a second problem.
Next, click this to search “tag” in ros-perception/ar_track_alvar, you will see this error:
Sorry, forked repositories are not currently searchable.
As you can see, it is impossible to search in the other repository because github thinks this is the main repository, which is a problem that gets worse as the forked repository evolves.
Tansferring is the correct solution, then deleting and reuploading without a fork is a good backup, though this will still have the problem in all other existing forks. Therefore, a transfer is the only way github will correctly reflect the new primary development repository, such as GitHub - ros-perception/ar_track_alvar: AR tag tracking library for ROS. These are the reasons I advise making every effort to see if owners will agree to and make an ownership transfer, and I’m sure many owners would agree once these problems are explained!
As a backup I suggest the ROS team delete and upload from their local clone, with a link/credit to the original authors in the README. This will enable search and allow other users who fork to point back to the new source of ROS development.