order=0 ski.transform.warp does not utilize fast code path

[stefanv]

Description:

To change to internal interpolation:

diff --git a/skimage/transform/_warps.py b/skimage/transform/_warps.py
index d7b38efdb..2fcfb7ed2 100644
--- a/skimage/transform/_warps.py
+++ b/skimage/transform/_warps.py
@@ -920,7 +920,7 @@ def warp(

     order = _validate_interpolation_order(image.dtype, order)

-    if order > 0:
+    if order >= 0:
         image = convert_to_float(image, preserve_range)
         if image.dtype == np.float16:
             image = image.astype(np.float32)
@@ -947,7 +947,7 @@ def warp(
             "to use bi-linear or bi-cubic interpolation instead."
         )

-    if order in (1, 3) and not map_args:
+    if order in (0, 1, 3) and not map_args:
         # use fast Cython version for specific interpolation orders and input

         matrix = None

Otherwise map_coordinates is used.

Way to reproduce:

No response

Version information:

No response