yarn run behaves differently than npm run

[pscanf]

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

Bug

What is the current behavior?

Running npm scripts with yarn yields a different result than running them with npm. Seems like the issue could be caused by #6650.

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

See reproduction repo https://github.com/pscanf/yarn-run-bug

What is the expected behavior?

Running npm scripts with yarn should have the same result as running them with npm.

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

node v10.13.0
yarn v1.12.3
macOS Sierra 10.12.6