check for head ref

.github/workflows/run-tests.yaml

@@ -66,6 +66,10 @@ jobs:
           pip install -r requirements-dev.txt
       - name: Test
         run: |
+          if [ -z "$GITHUB_HEAD_REF" ]
+          then
+            export GITHUB_HEAD_REF="main"
+          fi
           export MODEL_NAME=bloom-testing/test-bloomd-350m-$GITHUB_HEAD_REF
           python -m cli.run_server --converted_model_name_or_path $MODEL_NAME --block_indices 0:12 \
             --torch_dtype float32 --identity tests/test.id --host_maddrs /ip4/127.0.0.1/tcp/31337 --throughput 1 &