In order to support cargo clone (#1545) or any cargo vendor solution where the project has a crates.io reference, we will need to discover the git link in order to make a local clone of the repository.

It would be great if we could either put these in Cargo.toml and have them available in the published crate or (even better!) push the metadata up automagically during cargo publish, since there's a bit of a chicken-and-egg problem of needing to have the hash but not having the hash until the change is committed :-) Also open to other solutions, since we've discussed this need in the past and one of you might already have thought about something even smoother.

cc @alexcrichton @wycats