The intent of the previous version of the SFTP directory listing code
was to break the JSON transfer at blob boundaries, waiting for an ack
before sending the next blob, however the ordering of the "blob_written"
and directory read checks could result in a directory entry being
skipped at the boundary of each blob.
The proper order would be to check the "blob_written" flag first,
however the "blob_written" flag is unnecessary. It's simpler and more
correct to just break out of the loop once the desired blob has been
flushed.
