RuntimeError: dictionary changed size during iteration

[return42]

Really rare but from time to time we have a

RuntimeError: dictionary changed size during iteration

in the CI [1]. The full traceback is shown below. The issue appears while building the documentation make docs.

First reported by @dalf [2] in March 2022, but I have been seeing this error for a bit longer [3]

[1] https://github.com/searxng/searxng/runs/6931810805?check_suite_focus=true#step:6:624
[2] #930 (comment)
[3] #930 (comment)

Traceback (most recent call last):
  File "/home/runner/work/searxng/searxng/local/py3/lib/python3.9/site-packages/sphinx/config.py", line 332, in eval_config_file
    exec(code, namespace)
  File "/home/runner/work/searxng/searxng/docs/conf.py", line 49, in <module>
    searx.engines.load_engines(searx.settings['engines'])
  File "/home/runner/work/searxng/searxng/searx/engines/__init__.py", line 292, in load_engines
    engine = load_engine(engine_data)
  File "/home/runner/work/searxng/searxng/searx/engines/__init__.py", line 139, in load_engine
    set_loggers(engine, engine_name)
  File "/home/runner/work/searxng/searxng/searx/engines/__init__.py", line 152, in set_loggers
    for module_name, module in sys.modules.items():
RuntimeError: dictionary changed size during iteration