xarray rolling does not match pandas when using min_periods and reduce

MCVE Code Sample

MCVE

import numpy as np
import pandas as pd
import xarray

def custom(x, axis=0):
    return np.mean(x, axis)

d = pd.DataFrame(np.random.rand(100,3))
r = d.rolling(10, min_periods=5).apply(custom)
print(r.iloc[0:10,:])

xd = d.to_xarray().to_array()
r = xd.rolling(index=10, min_periods=5).reduce(custom)
print(r[:,0:10])
r = xd.rolling(index=10, min_periods=1).reduce(custom)
print(r[:,0:10])

Problem Description

I am applying a custom function on rolling windows with specific min_periods. The output of pandas..rolling.apply matches what I expect; however, the output of xarray..rolling.reduce doesn't seem to take min_periods into account.

Expected Output and Actual Output

          0         1         2
0       NaN       NaN       NaN
1       NaN       NaN       NaN
2       NaN       NaN       NaN
3       NaN       NaN       NaN
4  0.632168  0.523669  0.543643
5  0.558694  0.565781  0.481204
6  0.559343  0.541787  0.415490
7  0.613457  0.554888  0.398999
8  0.579552  0.496799  0.397681
9  0.562591  0.525096  0.416461
<xarray.DataArray (variable: 3, index: 10)>
array([[     nan,      nan,      nan,      nan,      nan,      nan,      nan,
             nan,      nan, 0.562591],
       [     nan,      nan,      nan,      nan,      nan,      nan,      nan,
             nan,      nan, 0.525096],
       [     nan,      nan,      nan,      nan,      nan,      nan,      nan,
             nan,      nan, 0.416461]])
Coordinates:
  * index     (index) int64 0 1 2 3 4 5 6 7 8 9
  * variable  (variable) int64 0 1 2
<xarray.DataArray (variable: 3, index: 10)>
array([[     nan,      nan,      nan,      nan,      nan,      nan,      nan,
             nan,      nan, 0.562591],
       [     nan,      nan,      nan,      nan,      nan,      nan,      nan,
             nan,      nan, 0.525096],
       [     nan,      nan,      nan,      nan,      nan,      nan,      nan,
             nan,      nan, 0.416461]])
Coordinates:
  * index     (index) int64 0 1 2 3 4 5 6 7 8 9
  * variable  (variable) int64 0 1 2

Output of xr.show_versions()

Reproduce the MCVE using pandas rolling.apply and xarray rolling.reduce with custom and different min_periods values. Start at the rolling reduce entry point, then verify that the xarray results apply the requested minimum valid-window count and match the expected output shown.