[pypy-issue] Issue #3089: regular expression ".split" does not work with look-ahead groups (pypy/pypy)

[João Sebastião de Oliveira Bueno]

New issue 3089: regular expression ".split" does not work with look-ahead groups
https://bitbucket.org/pypy/pypy/issues/3089/regular-expression-split-does-not-work

João Sebastião de Oliveira Bueno:

This are the results in cPython:  

```
>>> import re
>>> re.split("(?=3)", "12345")
['12', '345']
```

And this is what I get in pypy3:  

```python
>>>> import re
>>>> re.split("(?=3)", "12345")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib64/pypy3-7.0/lib-python/3/re.py", line 203, in split
    return _compile(pattern, flags).split(string, maxsplit)
ValueError: split() requires a non-empty pattern match.
```

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