Rename index.mjs to _index.mjs in @babel/runtime

[nicolo-ribaudo]

Q	A
Fixed Issues?	fix #12854, fix #12853
Patch: Bug Fix?
Major: Breaking Change?
Minor: New Feature?
Tests Added + Pass?	Yes
Documentation PR Link
Any Dependency Changes?
License	MIT

This should fix #12854, but for some reason webpack still loads the .mjs version when using require() 🤔
Maybe it's a caching problem, but what I see locally is that even uses the .mjs version even if I remove every mention of .mjs in @babel/runtime's package.json

The problem is that Webpack 4 always loads index.mjs if there are both index.js and index.mjs, and there is no way (unless you update the webpack config) to tell it to load index.js.

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[nicolo-ribaudo]

I can confirm that this works in my local gatsby project.

[KyleAMathews]

Thanks 🙏

[nicolo-ribaudo]

@KyleAMathews We are releasing (https://github.com/babel/babel/actions/runs/591028231)

[babel-bot]

Build successful! You can test your changes in the REPL here: https://babeljs.io/repl/build/41949/

[KyleAMathews]

@nicolo-ribaudo thanks so much! Confirmed Gatsby is back in business with 7.13.1 🎉

[nicolo-ribaudo]

I'm going to sleep now, but tomorrow I'll DM you to see how we can add Gatsby as an e2e test 😬

[KyleAMathews]

Excellent!

[DSchau]

@nicolo-ribaudo thank you truly for the quick turnaround on this.

We at Gatsby appreciate this, and so too do our users. We'd love to chat about e2e test, so let us know how we can help ensure we can automate and track this case for the future 👍