fetch: fix --bottle-tag when unbottled on host system

[FnControlOption]

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This can be tested by opening a formula, deleting/commenting out the bottle sha256 for your macOS version, and then running brew fetch --bottle-tag=<different macOS tag> <formula name>

[MikeMcQuaid]

This can be tested by opening a formula, deleting/commenting out the bottle sha256 for your macOS version, and then running brew fetch --bottle-tag=<different macOS tag> <formula name>

@FnControlOption Can you elaborate on the use-case for this? Thanks!

[FnControlOption]

Well, you're not gonna like this but... my use case for this was to download the molten-vk Catalina bottle so I could install it on a Mojave system. The project I was working on still didn't build though, so it wasn't really useful in the end.

On a slightly unrelated note, what other alternatives are there to download bottles? I can't find any direct download links at https://github.com/orgs/Homebrew/packages

[MikeMcQuaid]

deleting/commenting out the bottle sha256 for your macOS version

Does this still work if you don't do this?

Well, you're not gonna like this but... my use case for this was to download the molten-vk Catalina bottle so I could install it on a Mojave system.

I don't mind this being indirectly enabled but just not supported directly.

I can't find any direct download links at https://github.com/orgs/Homebrew/packages

formulae.brew.sh provides some links in the API. They may or may not work for a direct curl, though, as you have to set headers etc.

[FnControlOption]

deleting/commenting out the bottle sha256 for your macOS version

Does this still work if you don't do this?

Yes, this should continue functioning as before. I assumed you're already on a newer macOS where most formulae are already bottled, so I included that step in case you couldn't find an unbottled formula for your macOS version.

[MikeMcQuaid]

Seems fine to me, thanks @FnControlOption!