intermittent issue in feature_bip68_sequence.py: sequence_value = utxos[j]["confirmations"] IndexError: list index out of range #32334

https://cirrus-ci.com/task/5337593233014784?logs=ci#L3671

 test  2025-04-23T20:13:04.883000Z TestFramework (ERROR): Unexpected exception caught during testing 
                                   Traceback (most recent call last):
                                     File "/ci_container_base/test/functional/test_framework/test_framework.py", line 182, in main
                                       self.run_test()
                                     File "/ci_container_base/ci/scratch/build-i686-pc-linux-gnu/test/functional/feature_bip68_sequence.py", line 70, in run_test
                                       self.test_sequence_lock_confirmed_inputs()
                                     File "/ci_container_base/ci/scratch/build-i686-pc-linux-gnu/test/functional/feature_bip68_sequence.py", line 173, in test_sequence_lock_confirmed_inputs
                                       sequence_value = utxos[j]["confirmations"]
                                                        ~~~~~^^^
                                   IndexError: list index out of range

I can reproduce this issue locally by passing the randomseed as shown in the CI logs, i.e.

$ ./build/test/functional/feature_bip68_sequence.py --randomseed 6169832640268785903

Seems that the number of UTXOs generated in the test_sequence_lock_confirmed_inputs sub-test (currently 200) is not enough in some cases. A simple minimal-diff fix might be to simply increase that number in this line:

https://github.com/bitcoin/bitcoin/blob/458720e5e98c6e9103aea1fdfcd39bafc26c27bb/test/functional/feature_bip68_sequence.py#L137

IIUC, in the absolute worst-case 4000 UTXOs are consumed (400 txs with 10 inputs each).