Two Very Close Regexes With Lookahead Assertions In Python - Why Does Re.split() Behave Differently?

I was trying to anser this question where the OP has the following string: 'path:bte00250 Alanine, aspartate and glutamate metabolism path:bte00330 Arginine and proline metabolism'

Solution 1:

Python's re.split() has a documented limitation: It can't split on zero-length matches. Therefore the split only worked with the added space.