Sync intro-to-threading with the updated tutorial

[realpython-bot]

Syncs intro-to-threading/ with the maintenance update of An Intro to Threading in Python.

Changes

• single_thread.py: x.start() was commented out and x.join() was active, so the script crashed with RuntimeError: cannot join thread before it is started. Now matches the tutorial's first listing (start the thread, join commented out).
• fixrace.py: log messages now read Testing update. to match the tutorial, which says the calling code stays the same as in racecond.py and whose output now shows Testing update..
• prodcom_better_queue.py: consumer() checked the global pipeline.empty() instead of its own queue parameter. Now uses queue.empty(), as in the tutorial.

Links

• Draft update (admin): https://realpython.com/pbjt/blog/post/2526/change/
• Maintenance card: https://trello.com/c/hQq7My1Y

Verification

• Ran every script in the folder on Python 3.14.6 (stdlib only, no requirements). All exit cleanly, including single_thread.py, which crashed before.
• uvx ruff@0.14.1 format --check intro-to-threading and uvx ruff@0.14.1 check intro-to-threading both pass.

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