fix broken nn_convolution test (#166666)

Summary: Broken by oss diff during oncall by third party contributor

Test Plan: buck test 'fbcode//mode/dev-nosan' fbcode//caffe2/test:nn_convolution -- --run-disabled

Differential Revision: D85899891

Pull Request resolved: https://github.com/pytorch/pytorch/pull/166666
Approved by: https://github.com/atalman, https://github.com/seemethere, https://github.com/Skylion007

test/nn/test_convolution.py

@@ -12,6 +12,16 @@ import torch.backends.cudnn as cudnn
 import torch.nn as nn
 import torch.nn.functional as F
 from torch.testing import make_tensor
+
+
+def _get_cudnn_version():
+    """Safely get cuDNN version, returning None if unavailable."""
+    try:
+        return torch.backends.cudnn.version()
+    except RuntimeError:
+        return None
+
+
 from torch.testing._internal.common_cuda import TEST_CUDA, TEST_CUDNN, tf32_on_and_off
 from torch.testing._internal.common_device_type import (
     disablecuDNN,
@@ -4210,10 +4220,7 @@ class TestConvolutionNNDeviceType(NNTestCase):
     @largeTensorTest("20GB")
     @largeTensorTest("64GB", "cpu")
     # TODO(eqy): Remove this once it is fixed in cuDNN and we can dispatch to it again
-    @xfailIf(
-        torch.backends.cudnn.version() is not None
-        and torch.backends.cudnn.version() > 91000
-    )
+    @xfailIf(_get_cudnn_version() is not None and _get_cudnn_version() > 91000)
     def test_depthwise_conv_64bit_indexing(self, device):
         x = torch.randn(1, 2, 32800, 32800, dtype=torch.half).to(
             memory_format=torch.channels_last