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

What is the current behavior?
yarn global upgrade-interactive creates a package.json and yarn.lock in the folder that you invoke the command
If the current behavior is a bug, please provide the steps to reproduce.

• Have some globally installed outdated packages
• Go to a folder
• Invoke yarn global upgrade-interactive

What is the expected behavior?
No yarn.lock and package.json are generated if upgrade-interactive is invoked with the global property
Please mention your node.js, yarn and operating system version.
Node: 8.6.0
Yarn: 1.2.1
OS: Ubuntu 16.04