Fix non-existent variable, remove unused import. (#106)

* Fix non-existent variable, remove unused import.

* Adjust fix to be simpler.

Co-authored-by: Chris Anderson <cranderson@verisk.com>

Author: Chris Anderson

pointnet2_ops_lib/pointnet2_ops/pointnet2_utils.py

@@ -1,10 +1,8 @@
-import sys
-import warnings
-from typing import *
-
 import torch
 import torch.nn as nn
+import warnings
 from torch.autograd import Function
+from typing import *
 
 try:
     import pointnet2_ops._ext as _ext
@@ -124,7 +122,7 @@ def forward(ctx, unknown, known):
             (B, n, 3) index of 3 nearest neighbors
         """
         dist2, idx = _ext.three_nn(unknown, known)
-        dist = torch.sqrt(dist)
+        dist = torch.sqrt(dist2)
 
         ctx.mark_non_differentiable(dist, idx)