Failed to load mio/url during reload

[kjeremy]

I started rust-analyzer and noticed the following in the log:

[ERROR rust_analyzer::reload] failed to load C:\Users\jkolb\.cargo\registry\src\github.com-1ecc6299db9ec823\mio-0.6.22\test/mod.rs
[ERROR rust_analyzer::reload] failed to load C:\Users\jkolb\.cargo\registry\src\github.com-1ecc6299db9ec823\url-2.2.0\benches/parse_url.rs

[jonas-schievink]

This happens because those files are not included in the Cargo package (because the crates use include), but the files are still referenced in Cargo.toml, so it's a benign error (maybe it should be a warning instead?).