The problem is manifesting itself on Windows, but only because the FileSystemBinaryStore tries to rename a temporary file to move it into the FileSystemBinaryStore's storage area. Thus, because the rename doesn't work on Windows, the FileSystemBinaryStore reverts to copying via streaming. This copying process works, but is taking far too long.

We need separate tests that verify the copy logic we're using is fast enough, and that we're correctly buffering the content when streaming.