mach/libs/core/.github/pull_request_template.md

Please send your change to the main repository instead, sorry for the trouble!

This helps us avoid some complex merge conflicts we run into when changes are made to both repositories and history needs to be reconciled. Keeping PRs in just that repository enables us to use git subtree to trivially keep the two repositories in sync.

Once your PR is merged over there, it'll automatically sync to this repository.