Allow `dvc fetch` to target checksums directly

In my understanding, dvc files are good targets because they store data files checksums. It’s ergonomic, they work like refs in git.

But I think we should be able to fetch files also by checksum directly, no matter the current state of the workspace. In git, you can fetch a ref but you can also fetch a specific commit by hash.

My use case is that I have my own diff tooling, which is used by reference testing, that compares the current version of the dataset with the previous version reading it directly from the cache. If the file is not there, currently I have to checkout that commit in git before doing a dvc fetch and then checkout back, which is often impossible because I have pending changes.

[villasv]

The issue itself was not implemented, though it’s not needed anymore. IMO we can close it 😉

[efiop]

@villasv In that case, should we close this issue for now? 😃