False positive regression for `unused_crate_dependencies`

[robertbastian]

In beta (1.91.0-beta.3 (24bb93c38 2025-09-10)), there is a false positive from the unused_crate_dependencies lint that does not happen on 1.90.

To reproduce:

• clone https://github.com/unicode-org/icu4x at 292384d6a04746164faee7d660e75a5c7ca2b89c
• RUSTFLAGS="-D unused_crate_dependencies" cargo check --all-features --manifest-path components/properties/Cargo.toml
  • ✅
• RUSTFLAGS="-D unused_crate_dependencies" cargo +beta check --all-features --manifest-path components/properties/Cargo.toml

error: extern crate `icu_locale_core` is unused in crate `icu_properties`
 --> components/properties/src/lib.rs:5:1
  |
5 | //! Definitions of [Unicode Properties] and APIs for
  | ^
  |
  = help: remove the dependency or add `use icu_locale_core as _;` to the crate root
  = note: requested on the command line with `-D unused-crate-dependencies`

error: could not compile `icu_properties` (lib) due to 1 previous error

This crate is used, so it's regression, not a bug fix.

[lukaslueg]

Bisects to #144793, cc @petrochenkov

searched nightlies: from nightly-2025-06-23 to nightly-2025-09-26
regressed nightly: nightly-2025-08-15
searched commit range: 3672a55...898aff7
regressed commit: 8e77954

[apiraino]

Assigning priority (discussion on Zulip).

@rustbot label -I-prioritize +P-medium