provenance of recipe_hyint_extreme_events.yml broken

[mattiarighi]

Traceback (most recent call last):
  File "/mnt/lustre02/work/bd0080/b309057/SOFTWARE/miniconda3/envs/esmvaltool/lib/python3.8/multiprocessing/pool.py", line 125, in worker
    result = (True, func(*args, **kwds))
  File "/mnt/lustre01/pf/b/b309057/ESMValTool/core/esmvalcore/_task.py", line 723, in _run_task
    output_files = task.run()
  File "/mnt/lustre01/pf/b/b309057/ESMValTool/core/esmvalcore/_task.py", line 242, in run
    self.output_files = self._run(input_files)
  File "/mnt/lustre01/pf/b/b309057/ESMValTool/core/esmvalcore/_task.py", line 520, in _run
    self._collect_provenance()
  File "/mnt/lustre01/pf/b/b309057/ESMValTool/core/esmvalcore/_task.py", line 583, in _collect_provenance
    if ancestor_file in ancestor_products:
TypeError: unhashable type: 'list'

Same problem as reported in #1705 apparently.