Linux binary wheels have two copies of libspatialindex

[mwtoews]

Looking at PyPI files for 1.0.1 it seems that the linux versions have two copies of libspatialindex.

For instance Rtree-1.0.1-cp39-cp39-manylinux_2_17_x86_64.manylinux2014_x86_64.whl has:

.
├── rtree
│   ├── core.py
│   ├── exceptions.py
│   ├── finder.py
│   ├── index.py
│   ├── __init__.py
│   ├── lib
│   │   ├── libspatialindex_c.so
│   │   └── libspatialindex.so
│   └── py.typed
├── Rtree-1.0.1.dist-info
│   ├── LICENSE.txt
│   ├── METADATA
│   ├── RECORD
│   ├── top_level.txt
│   └── WHEEL
└── Rtree.libs
    └── libspatialindex-91fc2909.so.6.1.1

both Windows and macOS binary wheels only have one copy in rtree/lib.

On Linux, cibuildwheel uses auditwheel to copy external shared libraries. The cibuildwheel stuff should be fixed to not install rtree/lib for Linux, which may require changes to rtree.finder. Or, perhaps the bundled libraries in rtree/lib are preferred and auditwheel's Rtree.libs should be removed somehow.

Presently only the rtree/lib libraries are used from these PyPI binary wheels:

$ python -c "from rtree import finder; print(finder.load())"
<CDLL '/tmp/py39/lib/python3.9/site-packages/rtree/lib/libspatialindex_c.so', handle 56400f603870 at 0x7ff4184bb3a0>

[hobu]

I think this was an artifact of how the library used to be found and installed. If there's a better/modern way to do this, please update the build configuration.