Comment 0 for bug 2029411

The binary wheels published on PyPI starting with lxml 4.9.3 have a wrong hardcoded default path for the XML catalog file. This causes XML schema discovery to fail unless the XML catalog is specified manually using the `XML_CATALOG_FILES` environment variable. The hardcoded path is compiled as part of the statically linked libxml2, and it defaults to `%{sysconfdir}/xml/catalog`. In newer wheels this points to a temporary build directory instead of `/etc/xml/catalog`.

This can be checked by downloading a whl file from [PyPI](https://pypi.org/project/lxml/#files) and extracting the `etree` dynamic library and looking up the string:

```
# From lxml-4.9.3-pp310-pypy310_pp73-manylinux_2_28_x86_64.whl
❯ strings etree.pypy310-pp73-x86_64-linux-gnu.so | grep "/xml/catalog"
file:///tmp/pip-req-build-svyupjhx/build/tmp/libxml2/etc/xml/catalog

# From lxml-4.9.2-pp39-pypy39_pp73-manylinux_2_17_x86_64.manylinux2014_x86_64.manylinux_2_24_x86_64.whl
❯ strings etree.pypy39-pp73-x86_64-linux-gnu.so | grep "/xml/catalog"
file:///etc/xml/catalog
```

Possibly a result of CI changes?