That's only applicable if you use crates directly from GitHub repositories right? I've been sitting and developing+building a Rust project for the last +10 hours (except the minutes when I was here arguing on HN) and never hit any issues, but I'm using crates either directly from disk (cloned from GitHub initially) or from crates.io.
I could be wrong, but try a fresh build with a clean CARGO_HOME (or maybe just a cargo update?). It seems to query a lot if you don't have a full cache.