Simple, when performing various git annex command over ssh, in particular a multi-file get, and using password authentication, git annex will prompt more than once for a user password.  This makes batch updates very inconvenient.

> I'd suggest using ssh-agent, or a passwordless ssh key. Possibly in
> combination with [[git-annex-shell]] if you want to lock down a
> particular ssh key to only being able to use git-annex and git-daemon.
> 
> Combining multiple operations into a single ssh is on the todo list, but
> very far down it. --[[Joey]]

>> OTOH, automatically running ssh in ControlMaster mode (and stopping it
>> at exit) would be useful and not hard thing for git-annex to do.
>> 
>> It'd just need to set the appropriate config options, setting
>> ControlPath to a per-remote socket location that includes git-annex's
>> pid. Then at shutdown, run `ssh -O exit` on each such socket.
>> 
>> Complicated slightly by not doing this if the user has already set up
>> more broad ssh connection caching. --[[Joey]]