pandas bug: rolling_sum and rolling_mean

data.npy

test.py

import numpy as np
import pandas

data = np.load('data.npy')
assert all(data >= 0)

sums = pandas.rolling_sum(data, 2, min_periods=1)
zero = np.where(sums < 0)[0]
assert len(zero) == 0, zero

mean = pandas.rolling_mean(data, 2, min_periods=1)
zero = np.where(mean < 0)[0]
assert len(zero) == 0, zero