Prefer nvidia channel for conda builds (#5648)

To mitigate missing `libcupti.so` dependency

.circleci/unittest/linux/scripts/install.sh

@@ -21,7 +21,7 @@ else
     fi
     echo "Using CUDA $CUDA_VERSION as determined by CU_VERSION"
     version="$(python -c "print('.'.join(\"${CUDA_VERSION}\".split('.')[:2]))")"
-    cudatoolkit="cudatoolkit=${version}"
+    cudatoolkit="nvidia::cudatoolkit=${version}"
 fi
 
 case "$(uname -s)" in
@@ -33,7 +33,7 @@ printf "Installing PyTorch with %s\n" "${cudatoolkit}"
 if [ "${os}" == "MacOSX" ]; then
     conda install -y -c "pytorch-${UPLOAD_CHANNEL}" "pytorch-${UPLOAD_CHANNEL}"::pytorch "${cudatoolkit}" pytest
 else
-    conda install -y -c "pytorch-${UPLOAD_CHANNEL}" "pytorch-${UPLOAD_CHANNEL}"::pytorch[build="*${version}*"] "${cudatoolkit}" pytest
+    conda install -y -c "pytorch-${UPLOAD_CHANNEL}" -c nvidia "pytorch-${UPLOAD_CHANNEL}"::pytorch[build="*${version}*"] "${cudatoolkit}" pytest
 fi
 
 printf "* Installing torchvision\n"

packaging/build_cmake.sh

@@ -42,7 +42,7 @@ else
   PYTORCH_MUTEX_CONSTRAINT=''
 fi
 
-conda install -yq \pytorch=$PYTORCH_VERSION $CONDA_CUDATOOLKIT_CONSTRAINT $PYTORCH_MUTEX_CONSTRAINT $MKL_CONSTRAINT numpy -c "pytorch-${UPLOAD_CHANNEL}"
+conda install -yq \pytorch=$PYTORCH_VERSION $CONDA_CUDATOOLKIT_CONSTRAINT $PYTORCH_MUTEX_CONSTRAINT $MKL_CONSTRAINT numpy -c nvidia -c "pytorch-${UPLOAD_CHANNEL}"
 TORCH_PATH=$(dirname $(python -c "import torch; print(torch.__file__)"))
 
 if [[ "$(uname)" == Darwin || "$OSTYPE" == "msys" ]]; then

packaging/build_conda.sh

@@ -18,4 +18,4 @@ if [[ "$CU_VERSION" == cu115 ]]; then
     export CUDATOOLKIT_CHANNEL="conda-forge"
 fi
 
-conda build -c defaults -c $CUDATOOLKIT_CHANNEL $CONDA_CHANNEL_FLAGS --no-anaconda-upload --python "$PYTHON_VERSION" packaging/torchvision
+conda build -c $CUDATOOLKIT_CHANNEL -c defaults $CONDA_CHANNEL_FLAGS --no-anaconda-upload --python "$PYTHON_VERSION" packaging/torchvision