Weird kneibors behaviour

kneighbors_weired.py

from sklearn import datasets, manifold
from sklearn.neighbors import NearestNeighbors
import numpy as np


n_points = 1000
n_neighbors = 10
out_dim = 2 

n_trials = 100
X, _ = datasets.samples_generator.make_s_curve(n_points, random_state=123)
for i in xrange(n_trials):
    knn = NearestNeighbors(n_neighbors + 1).fit(X)
    print("with return")
    asdf = knn.kneighbors(X, return_distance=True) # will give no warning
    print("without return")
    knn.kneighbors(X, return_distance=True) # will give warning in second go of loop

    print(i)

with return
without return
0
with return
without return
1
with return
without return
Traceback (most recent call last):
File "testlle.py", line 15, in
knn.kneighbors(X, return_distance=True) # will give warning in second go of loop
File "/home/amueller/checkout/scikit-learn/sklearn/neighbors/base.py", line 225, in kneighbors
warn_equidistant()
File "/home/amueller/checkout/scikit-learn/sklearn/neighbors/base.py", line 23, in warn_equidistant
raise ValueError
ValueError