boto/boto — pull request #573 by psa (2012-02-10 17:14:20+00:00)
Title: Add a prefix to b.list() so s3put/s3multiput don't list the whole bucket

Listing the whole bucket to avoid overwriting keys is extremely
inefficient (especially for buckets will millions or billions of
objects). Use the path provided by the user to add a prefix to b.list()
so that the keyspace is reduced to just the area we're trying to sync.