Straggler due to list-after-write consistency

[ooq]

According to this post:
https://forums.aws.amazon.com/thread.jspa?messageID=687028#687028

S3 provides only eventual-consistency for list() operation after writes. This, according to my experience, might result in 20-30 seconds of delay for discovering the results of a finished task. One solution is to use get to fetch results after, say, 90% of tasks are finished.

I have a patch to fix this issue. Will make a PR.

[ericmjonas]

Fixed by PR #170