boto/boto — pull request #1012 by oozie (2012-09-24 14:31:35+00:00)
Title: Making 'oldest_date' parameter is mandatory.

The keyword parameter `oldest_date=` in `Layer1.list_open_workflow_executions` is mandatory, as per https://forums.aws.amazon.com/thread.jspa?threadID=95420
It's indeed OK to leave the closing value, `latest_date`, of the startTimeFilter range undefined, but `oldest_date` must be there.