Every so often, the crates.io index's Git history is squashed into one commit to minimize the history Cargo needs to download. When the index is squashed, we save snapshots to preserve the history of crate publishes.
Currently, those snapshots are stored as branches in the main index Git repository. Those branches are using server resources though, as the server still has to consider their contents whenever Cargo asks for the master branch. We will be deleting the snapshot branches from this repository to ensure that all objects referenced in the master branch will only be compressed against other objects in the master branch, ensuring that the current clone behavior will be much more efficient on the server side.
Here's how this might affect you:
If you use Cargo
You should not see any effects from this change. Cargo does not use the snapshot branches, and Cargo regularly handles index squashes. If you do see any issues, they are bugs, please report them on the Cargo repo.
If you use the snapshot branches
In one week, on 2022-02-21, we will be removing all snapshot branches from the crates.io-index repo. All snapshot branches, both historical and in the future, are and will be in the rust-lang/crates.io-index-archive repo instead. Please update any scripts or tools referencing the snapshot branches by that time.
In the future
In the medium term, we're working to prioritize the completion of in-progress work to add a way to serve the index as static files on HTTP, which will further ease the server load. The index repository will not be going away so that older versions of Cargo will continue to work. See RFC 2789 for more details.