#626 AbsurdSleepError from wait_for_parallel_branches incorrectly treated as task failure

In demo-matrix tests, wait_for_parallel_branches calls throw AbsurdSleepError which should suspend the task and resume when branch completes. However, the error is being treated as a task failure instead of a suspension. Observed log sequence: - [INFO] JOIN: Waiting for 5 parallel branches to complete - [INFO] Task suspended waiting for event - [ERROR] Task wait_pool failed after 1 attempts - AbsurdSleepError: Waiting for parallel branch to complete - RetryExhaustedException Expected: Task should suspend and resume when branch completes Actual: Task is suspended AND marked as failed simultaneously Affected tests (7/20 failing): pool_stress, parallel_counter_increment, checkpoint_conflict, fork_join_stress, nested_parallel, diamond_pattern, condition_with_parallel All use wait_for_parallel_branches pattern.