Revert "treewide: disable programs.nix-index.enable option by default"

[r-vdp]

Reverts #132

@trueNAHO this doesn't generate the error about the missing value for the enable option that I was expecting, it just defaults to false. I don't have time to look into it right now, so I'll just revert and we can re-do this again. Sorry about this.

[trueNAHO]

this doesn't generate the error about the missing value for the enable option that I was expecting, it just defaults to false.

I assume the error you meant is the one that was dropped in v9:

Including this option is also a future maintenance issue, we need to decide when to remove it (which will be again a breaking change for people who decided to set it), and it also doesn't make it clear which breaking change you're acknowledging, in case we introduce a new one before we remove this option.

So, I'd remove this option and just not provide a default for the enable option for now.

Alright. I dropped commit 395c618 ("shared: add programs.nix-index.acknowledgeBreakingChange option") in v9, if that is what you meant.

#132 (comment)

Is v8 the PR you actually wanted? I can re-open and rebase v8.

I don't have time to look into it right now, so I'll just revert and we can re-do this again. Sorry about this.

No worries.