And another, bit less pathological, testcase.  Sorry for the ugly testcase;  it was much worse before I boiled it down :-)

$ cat test.py 
import re, regex

text = "\nTest\nxyz\nxyz\nEnd"

regexp = '(\nTest(\n+.+?){0,2}?)?\n+End'
print re.findall(regexp, text)
print regex.findall(regexp, text)

$ python test.py
[('\nTest\nxyz\nxyz', '\nxyz')]
[('', '')]