artifact urls for scoped package format doesn't play nicely with yarn --offline

Describe the bug A clear and concise description of what the bug is.

verdaccio returns artifact urls for scoped packages that look like this: https://{verdaccio-url}/@babel%2fcode-frame/-/code-frame-7.0.0.tgz#06e2ab19bdb535385559aabb5ba59729482800f8

as opposed to in public registry:

https://registry.npmjs.org/@babel/code-frame/-/code-frame-7.0.0.tgz#06e2ab19bdb535385559aabb5ba59729482800f8

i.e. basically identical except verdaccio url encodes the scope/package as @babel%2fcode-frame instead of @babel/code-frame

But yarn’s regex for finding packages in its offline cache don’t work with this: https://github.com/yarnpkg/yarn/blob/master/src/fetchers/tarball-fetcher.js#L21

To Reproduce Steps to reproduce the behavior:

1. yarn add a scoped package
2. follow steps here to populate offline mirror

Expected behavior Offline mirror should have all the scoped packages.

Is there a reason why verdaccio url encodes the / there?

[juanpicado]

I think this can be closed https://github.com/yarnpkg/yarn/commit/b8af7e05acf965e612f2f8fafa240aa9bd069a41 https://github.com/yarnpkg/yarn/pull/7499 @moon-stripe please try again or 😃 just tell me so I can close this ticket.

[juanpicado]

@DanielRuf @zkochan I think he is aware https://twitter.com/arcanis/status/1131121028573388801