No s3 log when ssh ubuntu@i-xxxxxxxxxx

Hi,

when I start session via browser:
`https://eu-west-1.console.aws.amazon.com/systems-manager/session-manager/start-session?region=eu-west-1`

I get s3 output when session ends. The same way when I start session using `aws ssm start-session --target i-xxxxxxxxx`

But when I start session using `ssh ubuntu@i-xxxxxxxxxx`
session starts, but there is no audit log in s3.
Sessions stops with

```
[ubuntu@xxxxxxx ~]$ exit
logout
Connection to i-xxxxxxx closed.
Command '['session-manager-plugin', '{"SessionId": "xxxxxxxx", "TokenValue": "token", "StreamUrl": "wss://ssmmessages.eu-west-1.amazonaws.com/v1/data-channel/xxxxx?role=publish_subscribe", "ResponseMetadata": {"RequestId": "xxxxx", "HTTPStatusCode": 200, "HTTPHeaders": {"x-amzn-requestid": "xxxxxx", "content-type": "application/x-amz-json-1.1", "content-length": "690", "date": "Fri, 12 Jul 2019 10:05:40 GMT"}, "RetryAttempts": 0}}', 'eu-west-1', 'StartSession', '', '{"Target": "i-xxxxxx", "DocumentName": "AWS-StartSSHSession", "Parameters": {"portNumber": ["22"]}}', 'https://ssm.eu-west-1.amazonaws.com']' died with .
```

Can you please advise?

No file, test, or entry point is identified in the issue. Start by reproducing the browser, AWS CLI, and SSH session paths and trace the SSH Session Manager integration and S3 audit-log behavior. Done means determining why SSH sessions do not produce the expected S3 output and why the session-manager-plugin exits with SIGPIPE.

Written by the indexing model from the issue text.