Incomplete listing on Backblaze S3

[martinprikryl]

Contrary to AWS, Backblaze adds IsTruncated (and others) only after the CommonPrefixes and Contents. It's pagination is 1000, what is a multiple of libs3's MAX_COMMON_PREFIXES. So if you have prefixes-only listing, you get 125 callbacks with 32 commonPrefixes in each. None of them will have valid isTruncated yet. And in listBucketCompleteCallback, where isTruncated is finally known, both contentsCount and commonPrefixesCount will be zero, and the callback will not be triggered.

[martinprikryl]

Note that there's is probably a similar problem in multipart.c.