How to start syncing two existing directories with git annex?

[Adam Spiers]

On 24 November 2013 20:03, Sean Hammond <snhmnd at gmail.com> wrote:
> Hey, I have a ~/Music directory on computer A, and a ~/Music directory on
> computer B. They contain mostly the same files (and with the same paths).
> But there might be some files on A but not B, or vice-versa. And there might
> be some files on both but different (e.g. different id3 tags).
>
> I want to use git annex assistant to sync the two dirs. Neither computer is
> big enough to hold two copies of the Music dir at once. Ideally, I'd prefer
> not to have to delete the Music dir from computer B, for example, and then
> let git annex sync it from A over to B again.

This is a similar scenario to

http://git-annex.branchable.com/tips/migrating_two_seperate_disconnected_directories_to_git_annex/