Merge generated and manually maintained GYPI variables with copy and update
so the CLI works on Python 3 while preserving manual override precedence.
Add a hermetic CLI regression for exact output, progress diagnostics, and
unchanged repeated generation.
Add deterministic fixtures, goldens, and matching tests for all 18
make_* generators. Refactor make_distrib orchestration behind an
importable main entry point while preserving generated output. Add
passing characterizations for existing generator issues.
Marshall Greenblatt