Fix our CI's run-in-docker action for MPI (#1019)

.github/actions/run-in-docker/action.yml

@@ -13,6 +13,16 @@ runs:
   steps:
     - shell: bash
       run: |
-        docker run -i ${{ inputs.image }} ${{ inputs.shell }} -s << 'EOF'
+        # Note: "bash -s << EOF" does not play nice with mpirun/mpiexec. It
+        # silently skips any shell commands that come after the mpirun/mpiexec,
+        # so don't use it. Use this instead, which seems to work better.
+        tmpFile=$(mktemp)
+        cat > $tmpFile << 'EOF'
         ${{ inputs.run }}
         EOF
+        chown $(id -u):$(id -g) $tmpFile
+        container=$(docker run -id ${{ inputs.image }})
+        docker cp $tmpFile $container:$tmpFile
+        docker exec $container ${{ inputs.shell }} $tmpFile
+        docker stop $container
+        rm $tmpFile