fetch: add --bottle-tag flag

[dawidd6]

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It would be useful for maintainers to be able to easily fetch bottles for different OSes.

Not sure if the implementation itself is fine but it works.

[BrewTestBot]

Review period will end on 2021-07-13 at 00:00:00 UTC.

[Rylan12]

This should probably conflict with --build-from-source too, right?

[MikeMcQuaid]

Needs the change @Rylan12 mentioned but otherwise looks fine. This will get cleaned by brew cleanup but that should be fine. I assume it outputs the correct PATH?

[BrewTestBot]

Review period ended.

[dawidd6]

What do you mean by saying PATH? The famous env variable?

[carlocab]

I think Mike means the path to the downloaded bottle, as in the Downloaded to: line here:

❯ brew fetch hello
==> Downloading https://ghcr.io/v2/homebrew/core/hello/manifests/2.10
Already downloaded: /Users/carlocab/Library/Caches/Homebrew/downloads/93309a1636f67f0f51e2604bb2ece243b5a9324eda1d49e05192ed285af508cd--hello-2.10.bottle_manifest.json
==> Downloading https://ghcr.io/v2/homebrew/core/hello/blobs/sha256:69489ae397e4645127aa7773211310f81ebb6c99e1f8e3e22c5cdb55333f540
==> Downloading from https://pkg-containers.githubusercontent.com/ghcr1/blobs/sha256:69489ae397e4645127aa7773211310f81ebb6c99e1f8e3
######################################################################## 100.0%
Downloaded to: /Users/carlocab/Library/Caches/Homebrew/downloads/e0395c201b40d07f50d44b84fccab28bb89bb292929894555688f6510f583a4c--hello--2.10.big_sur.bottle.tar.gz
SHA256: 69489ae397e4645127aa7773211310f81ebb6c99e1f8e3e22c5cdb55333f5408

[carlocab]

Works great. 🎉 Thanks @dawidd6!

❯ brew fetch --bottle-tag=x86_64_linux hello
==> Downloading https://ghcr.io/v2/homebrew/core/hello/manifests/2.10
Already downloaded: /Users/carlocab/Library/Caches/Homebrew/downloads/93309a1636f67f0f51e2604bb2ece243b5a9324eda1d49e05192ed285af508cd--hello-2.10.bottle_manifest.json
==> Downloading https://ghcr.io/v2/homebrew/core/hello/blobs/sha256:e6980196298e0a9cfe4fa4e328a71a1869a4d5e1d31c38442150ed784cfc0e2
==> Downloading from https://pkg-containers.githubusercontent.com/ghcr1/blobs/sha256:e6980196298e0a9cfe4fa4e328a71a1869a4d5e1d31c38
######################################################################## 100.0%
Downloaded to: /Users/carlocab/Library/Caches/Homebrew/downloads/9c334d845e8a08c0d898b81ddd616360ffd4230df01b2ab5f2a61425d19a4bcd--hello--2.10.x86_64_linux.bottle.tar.gz
SHA256: e6980196298e0a9cfe4fa4e328a71a1869a4d5e1d31c38442150ed784cfc0e29

[MikeMcQuaid]

What do you mean by saying PATH? The famous env variable?

Apparently @carlocab can understand me even when I talk drivel! I have no idea why I capitalised that 😅