Use head SHA as ref in report

Author: pathawks

aws/sqs/process

@@ -50,7 +50,7 @@ REF="$BASE" ./bench || reportFailure
 aws sqs change-message-visibility --receipt-handle "$RECEIPT_HANDLE" --queue-url "$QUEUE_URL" --visibility-timeout 30
 
 # Generate report based on tests
-PR="$PR" REF="$BASE" ./report > "docs/$BASE.md"
+PR="$PR" REF="$HEAD_SHA" ./report > "docs/$BASE.md"
 cat "docs/$BASE.md"
 ./aws/s3/generate-and-upload-site
 rm "docs/$BASE.md"