Merge pull request scikit-learn#4456 from cgohlke/patch-1

[MRG + 1] Fix signature not compatible with previous declaration

Author: amueller

sklearn/neighbors/dist_metrics.pyx

@@ -981,10 +981,10 @@ cdef class HaversineDistance(DistanceMetric):
         return 2 * asin(sqrt(sin_0 * sin_0
                              + cos(x1[0]) * cos(x2[0]) * sin_1 * sin_1))
 
-    cdef inline DTYPE_t _rdist_to_dist(self, DTYPE_t rdist):
+    cdef inline DTYPE_t _rdist_to_dist(self, DTYPE_t rdist) except -1:
         return 2 * asin(sqrt(rdist))
 
-    cdef inline DTYPE_t _dist_to_rdist(self, DTYPE_t dist):
+    cdef inline DTYPE_t _dist_to_rdist(self, DTYPE_t dist) except -1:
         cdef DTYPE_t tmp = sin(0.5 * dist)
         return tmp * tmp