rayon-core-1.0.1 has been yanked.
Restricting multiple versions
In order to ensure proper coordination between threadpools, and especially
to make sure there's only one global threadpool, rayon-core is actively
restricted from building multiple versions of itself into a single target.
You may see a build error like this in violation:
error: native library `rayon-core` is being linked to by more
than one package, and can only be linked to by one package
While we strive to keep rayon-core semver-compatible, it's still
possible to arrive at this situation if different crates have overly
restrictive tilde or inequality requirements for rayon-core. The
conflicting requirements will need to be resolved before the build will
succeed.