Same trio 0.29 → 0.33 cancel-cascade slowdown that hit
`test_nested_multierrors` (ea67f1b6) — bumps the
`trio`-backend (non-debug, non-forking) budget in
`test_echoserver_detailed_mechanics` from 1s → 4s.
- The 1s budget raced the ~1s teardown deadline. On a
deadline-fire trio 0.33 injects
`Cancelled(source='deadline')` (cancel-reason
metadata) that wraps the mid-stream KBI in a
`BaseExceptionGroup`, breaking the bare
`pytest.raises(KeyboardInterrupt)` below.
- Bump matches the forking-spawner branch (4s).
- Inline NOTE references the tracking issue
`ai/conc-anal/trio_033_cancel_cascade_slowdown_depth3_issue.md`.
(this patch was generated in some part by [`claude-code`][claude-code-gh])
[claude-code-gh]: https://github.com/anthropics/claude-code
(cherry picked from commit d7da502d93)
(cherry picked from commit d0144e52cb)