Fixed horovod build

.github/workflows/hvd-tests.yml

@@ -56,9 +56,6 @@ jobs:
       - uses: actions/setup-python@v4
         with:
           python-version: ${{ matrix.python-version }}
-
-      - name: Setup tmate session
-        uses: mxschmitt/action-tmate@v3
 
       - name: Install dependencies
         shell: bash -l {0}
@@ -67,7 +64,20 @@ jobs:
           #install other dependencies
           pip install torch torchvision --index-url https://download.pytorch.org/whl/cpu
           pip install -r requirements-dev.txt
-          pip install git+https://github.com/horovod/horovod.git
+          
+          # Install Horovod from source and apply a patch to build with recent pytorch
+          # We can't use pip install <whatever> as build-env can't find pytorch and 
+          # `--no-build-isolation` does not work with horovod setup.py
+          git clone --recursive https://github.com/horovod/horovod.git /tmp/horovod
+          cd /tmp/horovod
+          sed -i "s/CMAKE_CXX_STANDARD 14/CMAKE_CXX_STANDARD 17/g" CMakeLists.txt
+          sed -i "s/CMAKE_CXX_STANDARD 14/CMAKE_CXX_STANDARD 17/g" horovod/torch/CMakeLists.txt          
+          HOROVOD_WITH_PYTORCH=1 python setup.py install                
+          cd -
+          # test the installation:
+          python -c "import horovod.torch as hvd; hvd.mpi_ops.Sum"
+
+          # Install ignite
           python setup.py install
 
       # Download MNIST: https://github.com/pytorch/ignite/issues/1737