diff -Nru dbus-1.10.6/debian/changelog dbus-1.10.6/debian/changelog
--- dbus-1.10.6/debian/changelog	2016-04-01 03:25:06.000000000 +0200
+++ dbus-1.10.6/debian/changelog	2016-05-24 13:16:44.000000000 +0200
@@ -1,3 +1,20 @@
+dbus (1.10.6-1ubuntu4) UNRELEASED; urgency=medium
+
+  * debian/dbus.user-session.upstart:
+    - Don't start a new session bus if there already is one (e. g. via
+      dbus-user-session), as this would lead to different services talking to
+      different buses and thus not seeing each other. As we still need the
+      actual job itself running, run "sleep infinity" instead in this case.
+    - Drop "expect fork" and "--fork" argument. There is little point in the
+      daemon forking, upstart already manages it. This makes debugging easier
+      and also avoids having to fork "sleep" in the case that dbus-daemon is
+      already running.
+    - Drop "mkdir ~/.cache/upstart". This doesn't belong into a job, isn't
+      necessary (upstart already creates it on start) and would be too late
+      anyway.
+
+ -- Martin Pitt <martin.pitt@ubuntu.com>  Tue, 24 May 2016 12:21:08 +0200
+
 dbus (1.10.6-1ubuntu3) xenial; urgency=medium
 
   * debian/dbus.preinst: divert the dbus-daemon-launch-helper if upgrading
diff -Nru dbus-1.10.6/debian/dbus.user-session.upstart dbus-1.10.6/debian/dbus.user-session.upstart
--- dbus-1.10.6/debian/dbus.user-session.upstart	2015-09-01 18:31:53.000000000 +0200
+++ dbus-1.10.6/debian/dbus.user-session.upstart	2016-05-24 13:22:44.000000000 +0200
@@ -6,17 +6,27 @@
 env DBUS_DEBUG_OUTPUT=1
 
 respawn
-expect fork
+
 pre-start script
-    DBUS_SESSION_BUS_ADDRESS=unix:abstract=$(mktemp -u /tmp/dbus-XXXXXXXXXX)
+    if [ -z "$DBUS_SESSION_BUS_ADDRESS" ]; then
+        DBUS_SESSION_BUS_ADDRESS=unix:abstract=$(mktemp -u /tmp/dbus-XXXXXXXXXX)
+        initctl set-env do_launch=1
+    fi
     initctl set-env DBUS_SESSION_BUS_ADDRESS=$DBUS_SESSION_BUS_ADDRESS
 end script
 
-exec dbus-daemon --fork --session --address="$DBUS_SESSION_BUS_ADDRESS"
+script
+    if [ -n "$do_launch" ]; then
+        exec dbus-daemon --session --address="$DBUS_SESSION_BUS_ADDRESS"
+    else
+        # if there already is an existing user bus, don't launch another one,
+        # but keep running to start jobs that trigger on dbus
+        exec sleep infinity
+    fi
+end script
 
 post-start script
     initctl set-env --global DBUS_SESSION_BUS_ADDRESS=$DBUS_SESSION_BUS_ADDRESS
-    [ -d "$HOME/.cache/upstart" ] || mkdir -p "$HOME/.cache/upstart" || true
     echo "DBUS_SESSION_BUS_ADDRESS=${DBUS_SESSION_BUS_ADDRESS}" >$XDG_RUNTIME_DIR/dbus-session || true
     initctl notify-dbus-address "$DBUS_SESSION_BUS_ADDRESS" || true
 end script