Bucket is created in another region. Looks like the aws cmdline tool is confused about the region: aws: error: argument --region: expected one argument.
The S3 sync is triggered by script cluster/aws/util.sh. The command executed is aws s3 sync --region ${s3_bucket_location} --exact-timestamps ${local_dir} "s3://${AWS_S3_BUCKET}/${staging_path}/".
You can add an echo ${s3_bucket_location} before the line above. It should give you more information on what the region is set to.