Lock should not be release on ignored exception

[dbernstein]

@jonathangreen : I ran into this one while fixing the issues you identified in my overdrive task fix PR.

Description

• lock.py: Fixes the lock() context manager so that when an exception in ignored_exceptions is raised, the lock is not released. Previously, ignored exceptions were treated as clean exits (exception_occurred=False), so release_on_exit and not exception_occurred evaluated to True and the lock was released. The fix adds ignored_exception_occurred tracking and skips the release when an ignored exception occurs.
• test_lock.py: Adds test_lock_not_released_on_ignored_exception, which asserts that the lock remains held when an exception in ignored_exceptions is raised. This test fails before the fix and passes after it.

Motivation and Context

The ignored_exceptions parameter is intended to keep the lock held when certain exceptions occur (e.g. Celery's Ignore from task.replace() or retry-related exceptions). With the old logic, the lock was still released for those exceptions, which could cause race conditions when retrying or chaining tasks.

How Has This Been Tested?

• Added test_lock_not_released_on_ignored_exception, which acquires a lock with ignored_exceptions=(ValueError,), raises ValueError inside the context manager, and asserts the lock is still held.
• Confirmed the test fails with the old implementation and passes with the fix.
• Ran the full lock test suite to ensure no regressions.

Checklist

• I have updated the documentation accordingly.
• All new and existing tests passed.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.28%. Comparing base (a5d2c7c) to head (290e8fc).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3165   +/-   ##
=======================================
  Coverage   93.28%   93.28%           
=======================================
  Files         493      493           
  Lines       45711    45713    +2     
  Branches     6264     6264           
=======================================
+ Hits        42641    42645    +4     
+ Misses       1983     1982    -1     
+ Partials     1087     1086    -1     

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[jonathangreen]

Looks good! Good catch.