str.split ignores n if pat is None (original) (raw)
as observed in: http://stackoverflow.com/questions/21998590/str.split ignores n if pat is None
relevant source code:
# pandas/core/strings.py
def str_split(arr, pat=None, n=None):
if pat is None:
if n is None or n == 0:
n = -1
f = lambda x: x.split()
....