When a crate B depends on a crate A as both a regular and build dependency, and then tries to reference crate A in its build.rs, rust-analyzer says there is an unresolved import. But, cargo is fine.
Here's a sample workspace that should reproduce the bug: hmm.zip
cargo build in the workspace root reports no errors but rust-analyzer does report an error:

- rust-analyzer version: 3022a2c 2021-05-24 stable
- client: vscode