Building a project with a dependency serde = "1.0" causes the following error:
error: no matching version `^1.0` found for package `serde`
location searched: registry `https://github.com/rust-lang/crates.io-index`
versions found: 0.9.6, 0.9.5, 0.9.4, ...
This might be caused by #5300 (cc @djc).