Message 194825 - Python tracker

> 2. Matthew said that Python's engine is not robust against _unbounded_ repeated matching of an empty sub-match, and so "That's the reason for the up-front check".  I was asking for an example of _that_ behavior.  I still haven't seen one.

Perhaps Matthew did not understand you or you did not understand Matthew. 
For non-greedy repeats this was fixed in issue9669 (thank to Matthew). For greedy repeats this was fixed some time before.