abi3 fallback for older interpreters incorrectly sets Py_LIMITED_API in pyo3 config

## Bug Description When maturin detects abi3 support and an interpreter older than the abi3 minimum is requested (e.g., Python 3.10 when abi3 targets ≥ 3.11), it falls back to building a version-specific wheel. However, the generated `pyo3-config-*.txt` for the fallback build still appears to have `abi3=true` set, which causes `Py_LIMITED_API` to be defined during compilation. This breaks crates that use pyo3 APIs gated behind `cfg(any(not(Py_LIMITED_API), Py_3_XX))` — for example, `pyo3::buffer` which requires either non-limited-API or Python ≥ 3.11. **This is a regression introduced in maturin 1.13.x** (likely related to #3126 "fall back to placeholder for abi3 when found interpreters are too old"). The same project builds successfully with maturin 1.12.6. ## Reproduction Project: https://github.com/trim21/bencode-rs/pull/240 ### pyproject.toml (relevant sections) ```toml [build-system] requires = ["maturin==1.13.2"] build-backend = "maturin" [tool.maturin] features = [ { feature = "pyo3/abi3-py311", python-version = ">=3.11" }, ] ``` ### Cargo.toml (relevant sections) ```toml [dependencies] pyo3 = { version = "0.28.3", features = ['generate-import-lib'] } ``` ### Build command ``` maturin build --release --out dist --interpreter '3.11' --interpreter '3.10' ``` ### Steps to reproduce 1. Use a pyo3 project that imports `pyo3::buffer` (which is gated behind `cfg(any(not(Py_LIMITED_API), Py_3_11))`) 2. Configure conditional abi3 features in `pyproject.toml`: `{ feature = "pyo3/abi3-py311", python-version = ">=3.11" }` 3. Build with `--interpreter '3.11' --interpreter '3.10'` ### Expected behavior - First build: abi3 wheel for Python ≥ 3.11 ✅ (works) - Second build: version-specific wheel for Python 3.10 with `abi3=false` in pyo3 config ✅ ### Actual behavior - First build: abi3 wheel for Python ≥ 3.11 ✅ (works) - Second build: version-specific wheel for Python 3.10, but the generated pyo3 config appears to still have `abi3=true`, causing `Py_LIMITED_API` to be defined ❌ ## Error output ``` 📦 Built wheel for abi3 Python ≥ 3.11 to dist/bencode_rs-0.0.9-cp311-abi3-manylinux_2_17_x86_64.manylinux2014_x86_64.whl ⚠️ Warning: abi3 does not yet support CPython 3.10 so the build artifacts will be version-specific. error[E0432]: unresolved import `pyo3::buffer` --> src/encode.rs:2:11 | 2 | use pyo3::buffer::{PyBuffer, ReadOnlyCell}; | ^^^^^^^ could not find `buffer` in `pyo3` | note: found an item that was configured out --> pyo3-0.28.3/src/lib.rs:413:9 | 413 | pub mod buffer; | ^^^^^^ | ::: pyo3-0.28.3/src/buffer.rs:1:11 | 1 | #![cfg(any(not(Py_LIMITED_API), Py_3_11))] | ------------------------------ the item is gated here ``` ## Environment - maturin version: 1.13.2 (regression from 1.12.6) - pyo3 version: 0.28.3 - Python interpreters: 3.10, 3.11 - Platforms affected: all (Linux x86_64, Linux aarch64, macOS arm64, etc.) ## CI Run Full CI failure logs: https://github.com/trim21/bencode-rs/actions/runs/25625690761