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

Bug.

What is the current behavior?

Yarn doesn't respect the npm-shrinkwrap.json contained inside added dependencies, like hapi, and chooses to install the latest semver compatible versions declared in its package.json instead.

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

yarn add <package-with-shrinkwrap>

What is the expected behavior?

Installation of the exact versions declared in npm-shrinkwrap.json, including sub-dependencies. Alternatively, a visible warning that the file has been ignored, and the install might be broken due to this.

Note that it is an important feature that a package can specify the exact dependency version requirements.

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

yarn v0.15.1