Suppose A is 10 mb, and B is 20 mb, and the upload speed is the same. If B
starts first, when A will overwrite the file it is uploading for the 1st chunk.
Then A uploads the second chunk, and once A is done, B finishes the 1st chunk
and uploads its second. We now have 1(from A), 2(from B), so data loss.
The benefit of using a compatable directory structure does not outweigh the
cost in complexity of handling the multiple locations content can be stored
in directory special remotes. And this also allows doing away with the parent
directories, which can't be made unwritable in DAV, so have no benefit
there. This will save 2 http calls per file store.
But, kept the directory hashing, just in case.
