[rustdoc-json] Regression — `core.json`, `alloc.json` and `std.json` are no longer available on nightly for `rust-docs-json` component

[LukeMathWalker]

I have pinned down the regression to a specific commit, thanks to @aDotInTheVoid recommending me cargo-bisect-rustc.

Output of cargo bisect-rustc

searched nightlies: from nightly-2024-07-28 to nightly-2024-07-30
regressed nightly: nightly-2024-07-30
searched commit range: 2cbbe8b...612a33f
regressed commit: 56c698c

bisected with cargo-bisect-rustc v0.6.9

Host triple: aarch64-apple-darwin
Reproduce with:

cargo bisect-rustc -c rust-docs-json --start=2024-07-28 --end=2024-07-30 --script ./regr.sh

regr.sh:

#!/bin/sh
set -ex

if [ ! -f ~/.rustup/toolchains/${RUSTUP_TOOLCHAIN}/share/doc/rust/json/core.json ]; then
    echo "File not found!"
    exit 1
fi

[LukeMathWalker]

Based on the commits in that rollup, I feel like #128182 might be the culprit, but it isn't obvious to me why that might be the case (cc @onur-ozkan, @ChrisDenton, @Mark-Simulacrum)

[onur-ozkan]

Thanks for the ping, #128631 will fix this.