awscli version "1.11.13-1ubuntu1~16.04.0" was installed with the Ubuntu package manager and run like:

aws s3 cp doc/html s3://BUCKET/PATH/HERE --recursive --acl public-read --region us-east-1

It successfully uploads all the files in the source directory except for one zero-byte file. It fails there with:

seek() takes 2 positional arguments but 3 were given