Pin Cython<3.3 for pyzmq source-build compat (3006.x) - #70121
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Cython 3.3.0 (published to PyPI 2026-08-22) tightened its parser and rejects variable redeclarations in pyzmq 27.1.0's cython sources (zmq/backend/cython/_zmq.py:357 'hint', :1112 'c_addr'). pyzmq is source-built under the relenv onedir toolchain (--no-binary=:all:), so pip's PEP-517 build-isolation env resolves Cython fresh from PyPI and picks up 3.3.0. Pin Cython<3.3 in requirements/constraints.txt and export the same file via PIP_BUILD_CONSTRAINT alongside PIP_CONSTRAINT everywhere it is set, because PIP_CONSTRAINT stopped propagating into build-isolation envs in pip 26.x (deprecated in 26.1, enforced in 26.2). Build tooling only; no runtime dependency changes.
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What broke
Cython 3.3.0 was published to PyPI on 2026-08-22. Its tightened parser
rejects variable redeclarations in pyzmq 27.1.0's cython sources:
pyzmq is source-built under the relenv onedir toolchain
(
--no-binary=:all:intools/pkg/build.py), so pip's PEP-517build-isolation env resolves Cython fresh from PyPI and picks up 3.3.0.
Every active branch's Build Onedir / Source Packages / Onedir Packages
jobs go red the same way.
Fix
Cython < 3.3torequirements/constraints.txt.PIP_BUILD_CONSTRAINTalongsidePIP_CONSTRAINTinnoxfile.pyandtools/pkg/build.py. Necessarybecause
PIP_CONSTRAINTstopped propagating into PEP-517build-isolation envs in pip 26.x (deprecated in 26.1, enforced in
26.2 -- pip 26.1.2 already prints the deprecation on every install).
Scope
Build-tooling only. No runtime dependency changes, no lock-file
regeneration, no Salt source touched.
Cross-branch
Same fix opened in parallel on 3007.x / 3008.x / master. Sibling PR
links to be added once all four are open.