fix parrots op bug (#1289)

mmcv/onnx/info.py

 # Copyright (c) OpenMMLab. All rights reserved.
 import os
 
+import torch
+
 
 def is_custom_op_loaded():
     flag = False
@@ -16,4 +18,4 @@ def is_custom_op_loaded():
             flag = os.path.exists(ort_lib_path)
         except (ImportError, ModuleNotFoundError):
             pass
-    return flag
+    return flag or torch.__version__ == 'parrots'

mmcv/ops/csrc/parrots/sync_bn_parrots.cpp

@@ -45,7 +45,7 @@ void sync_bn_forward_output_cuda_parrots(CudaContext& ctx,
   auto running_var = buildATensor(ctx, outs[1]);
   auto norm = buildATensor(ctx, outs[2]);
   auto std = buildATensor(ctx, outs[3]);
-  auto output = buildATensor(ctx, outs[3]);
+  auto output = buildATensor(ctx, outs[4]);
   sync_bn_forward_output_cuda(input, mean, var, running_mean, running_var,
                               weight, bias, norm, std, output, eps, momentum,
                               group_size);