Not possible to install zstd support extra without IA patched zstandard package

[ikreymer]

The zstd extra depends on a non-public package:

            # requires a version locally patched for correct single-frame decompression
            'zstandard==0.12.0+ia1'

Is it possible to release that package, or provide a workaround that doesn't depend on it?

Wanted to test indexing of warc.zst files.

[kngenie]

Patched python-zstandard is available at https://github.com/kngenie/python-zstandard/tree/0.12.0-ia
(there's also https://github.com/kngenie/python-zstandard/tree/0.15.0-ia that works with v4.0 of CDX-Writer).
Note CDX-Writer depends on CFFI version of the library. Make sure CFFI version is included by installing cffi in the build env and passing environment variable PYTHON_ZSTANDARD_IMPORT_POLICY=cffi.

Correction: the environment variable is for runtime - it is not necessary to include CFFI support at build time.

Note enabling CFFI support with 0.15.0 requires either pre-installing cffi + disabling build-isolation, or forcing the installation of cffi package by editing install_requires in setup.py. There may be easier way to do it, but that's what I did to get CFFI support included.