Dist rust: Crates fail with extern location for foo does not exist

[samuel-jimenez]

Certain crates fail with extern location for foo does not exist.
Minimal example: https://github.com/samuel-jimenez/sccache-extern.
The error seems to point to missing deps. May be a job scheduling problem?

[samuel-jimenez]

The root seems to be a failure in handling a library with crate-type = ["cdylib", "rlib"].
This triggers a CannotCache(crate-type, cdylib).
However, any crates that depend on the library do not wait for it to complete.

See: https://github.com/samuel-jimenez/sccache-cdy