Provenance of recipe_extreme_events.yml and recipe_extreme_index.yml broken

[mattiarighi]

Same error as in #1705, #1711, #1713, #1717

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'

[mattiarighi]

@earnone @jhardenberg any news here?

@katjaweigel would it be possible for you to implement the same fix of #1752 in extreme_events\extreme_events.R and magic_bsc\extreme_index.R?

[katjaweigel]

I'm testing it, branch fix_extreme_events_ancestor