Another option (to remove the ambiguity) could be to move the “group” after the expression. Bonus points for reading more clearly:
except MemoryError group as e: …
except (KeyError, IndexError) group as e: …
except some + expression group as e: …
Argh. This would be very easy to overlook. As the senior author of PEP 654 I am going to go with "except*". Since it was shown that "except group" has ambiguous edge cases the proposals have gotten worse, which to me is a good sign that we need to stop.