–frozen-lockfile is not failing as expected when a change is required from within a workspace

Do you want to request a feature or report a bug?

Bug

What is the current behavior?

When running yarn install --frozen-lockfile from a project using Yarn workspaces, the command will complete successfully without throwing an error, even if an update to the lockfile is required due to a dependency within a workspace.

If the current behavior is a bug, please provide the steps to reproduce.

@devrelm has created a repository to reproduce the problem: https://github.com/devrelm/frozen-lockfile

What is the expected behavior?

yarn install --frozen-lockfile should throw an error if an update to the lockfile is required.

Please mention your node.js, yarn and operating system version.

Yarn v1.9.4 (also tested with v1.0.0)
Node.js v8.1.11.3
Windows 10 build 17134.228