Handling crate updates

Hello everyone

I was wondering how the rust-sig / rust folks handle crate updates. 
Let's say you generate a spec file with `rust2rpm` and manually patch 
it. The reason is not important here. Then a week later the upstream 
releases a new version. How do you handle this? Do you regenerate the 
spec file with `rust2rpm` and reapply your patches or do you update the 
spec file yourself? Should this be documented in the "Rust Packaging 
Guidelines"?

Hussein