import(..., fromlist['']) is handled by code that swallows the exception. A comment notes "Backwards-compatibility dictates we ignore failed imports triggered by fromlist for modules that don't exist." https://github.com/python/cpython/blob/v3.12.2/Lib/importlib/_bootstrap.py#L1414-L1422 So I think it's a trick that became widespread in early Python (pre 2.x?), enough to be a grudgingly accepted unofficial API. I should specifically handle it as a corner case in Mitogen's find_spec(). #Python#Mitogen