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

1. 
   maflcko commented at 7:48 am on April 24, 2025: member

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

   0 test  2025-04-23T20:13:04.883000Z TestFramework (ERROR): Unexpected exception caught during testing 
   1                                   Traceback (most recent call last):
   2                                     File "/ci_container_base/test/functional/test_framework/test_framework.py", line 182, in main
   3                                       self.run_test()
   4                                     File "/ci_container_base/ci/scratch/build-i686-pc-linux-gnu/test/functional/feature_bip68_sequence.py", line 70, in run_test
   5                                       self.test_sequence_lock_confirmed_inputs()
   6                                     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
   7                                       sequence_value = utxos[j]["confirmations"]
   8                                                        ~~~~~^^^
   9                                   IndexError: list index out of range
   

2. maflcko added the label CI failed on Apr 24, 2025
3. 
   theStack commented at 2:59 pm on April 24, 2025: contributor

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

   0$ ./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).

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