Align empty cluster target handling

[GruffElixir]

What changed

The synchronous cluster client now treats empty target_nodes values the same way as the async client and pipeline implementation: they fall back to normal command-policy routing instead of being treated as an explicit empty target set.

Regression tests cover empty lists, mappings, and strings for both sync and async clients.

Fixes #4318.

Validation

• uv run --no-project --with pytest --with pytest-asyncio --with async-timeout python -m pytest tests/test_cluster.py tests/test_asyncio/test_cluster.py -q -k empty_target_nodes
• uv run --no-project --with ruff ruff check redis/cluster.py tests/test_cluster.py tests/test_asyncio/test_cluster.py
• git diff --check

---

Note

Low Risk
Single conditional change in cluster command routing with targeted regression tests; behavior aligns sync with existing async/pipeline semantics.

Overview
Fixes cluster routing when target_nodes is empty. The sync RedisCluster.execute_command path now uses if passed_targets instead of if passed_targets is not None, matching the async client and pipeline behavior.

Empty values ([], {}, "") are no longer treated as an explicit (empty) target set; commands fall back to normal policy routing and run on the default node.

Regression tests for sync and async assert DBSIZE with those empty target_nodes values delegates to _execute_command on the default node only.

Fixes #4318.

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[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Reject unsupported false-y target types

When target_nodes is False, 0, (), or b"", this condition now skips _parse_target_nodes; _determine_nodes also ignores the false-y node flag, so the command is dispatched using normal routing. Before this commit these unsupported types raised TypeError, which matters especially for writes because an invalid caller or configuration value now executes rather than failing fast. Limit the fallback to the deliberately accepted empty list, mapping, and string instead of all false-y objects, and mirror that validation in async.

AGENTS.md reference: AGENTS.md:L159-L163

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