Failure in defect_model.classify

[marco-c]

Traceback (most recent call last):
  File "/usr/local/bin/bugbug-regressor-finder", line 8, in <module>
    sys.exit(main())
  File "/usr/local/lib/python3.10/site-packages/scripts/regressor_finder.py", line 651, in main
    regressor_finder.find_bug_fixing_commits()
  File "/usr/local/lib/python3.10/site-packages/scripts/regressor_finder.py", line 276, in find_bug_fixing_commits
    classified_bugs = defect_model.classify(bugs_to_classify)
  File "/usr/local/lib/python3.10/site-packages/bugbug/model.py", line 629, in classify
    X = self.extraction_pipeline.transform(lambda: items)
  File "/usr/local/lib/python3.10/site-packages/sklearn/pipeline.py", line 635, in transform
    Xt = transform.transform(Xt)
  File "/usr/local/lib/python3.10/site-packages/bugbug/bug_features.py", line 737, in transform
    first_bug = next(bugs_iter)
TypeError: 'list' object is not an iterator

This is a regression from 9bc7dd0.