### Please describe the problem.

If the assistant daemon is killed, ssh mux sessions are left behind. Incidentally there may be a better way to stop the assistant daemon besides "killall git-annex" but I haven't found it in the docs.

### What steps will reproduce the problem?

[[!format sh """
$ ps aux | grep mux
$ git-annex assistant
$ date > fromwintermute # Just causing a change that needs to be pushed, any will do
$ ps aux | grep mux
pedrocr  32665  0.0  0.0   6396   948 ?        Ss   11:06   0:00 ssh: /home/pedrocr/testsync/.git/annex/ssh/golias.git-annex [mux]
$ killall git-annex
$ ps aux | grep mux
pedrocr  32665  0.0  0.0   6396   948 ?        Ss   11:06   0:00 ssh: /home/pedrocr/testsync/.git/annex/ssh/golias.git-annex [mux]
"""]]

### 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
"""]]



> [[done]] --[[Joey]]