### Please describe the problem.

The assistant seems to only sync files and not directories, so empty directories will not be synced.

### What steps will reproduce the problem?

- Create an empty directory on HostA
- See that nothing gets synced (daemon.log is silent) and the directory doesn't exist on the other HostB
- Create an empty file inside the empty directory on HostA
- See that now HostB has the empty file inside the directory

I'm sure this comes directly from the git behavior but is at least surprising for a direct mode repository using the assistant.

### What version of git-annex are you using? On what operating system?

[[!format sh """
$ git annex version
git-annex version: 4.20130516.1
build flags: Assistant Webapp Pairing Testsuite S3 WebDAV Inotify DBus XMPP
local repository version: 4
default repository version: 3
supported repository versions: 3 4
upgrade supported from repository versions: 0 1 2
$ lsb_release -a
No LSB modules are available.
Distributor ID:	Ubuntu
Description:	Ubuntu 12.04.2 LTS
Release:	12.04
Codename:	precise
"""]]
