Rust Packaging without crates.io

[Jonathan Scoresby]

I am trying to build a package definition for a rust project that is not on 
crates.io (package A). It has a dependency for another rust project that is 
also not hosted on crates.io (package B). How do I get guix to reference the 
guix package B instead of trying to fetch it from the source repository?

I'm new to guix but I took a look into the build system code, and it seems like 
guix just changes the crates.io source to a local repository, but this doesn't 
work with packages that are hosted outside crates.io.

Would it be best to modify the cargo.toml to not reference a git repo? Or is 
there a better way? Assuming I do that, how do I ensure that package B still 
ends up in the guix-vendor directory during the build?

Thanks