Add git info to nightly summary

Author: Alan Hanson

tools/test_nightly.sh

@@ -15,6 +15,7 @@ cd "$ROOT" || (echo failed to cd "$ROOT"; exit 1)
 export BINDIR=${BINDIR:-$ROOT/target/release}
 
 echo "Nightly starts at $(date)" | tee "$output_file"
+echo "Running on $(git log -1 | head -20)" | tee -a "$output_file"
 echo "$(date) hammer start" >> "$output_file"
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