diff -Nru dbus-1.9.20/debian/75dbus_dbus-launch dbus-1.9.20/debian/75dbus_dbus-launch
--- dbus-1.9.20/debian/75dbus_dbus-launch	2015-08-17 15:50:33.000000000 +0000
+++ dbus-1.9.20/debian/75dbus_dbus-launch	2015-08-18 15:10:16.000000000 +0000
@@ -7,7 +7,7 @@
 DBUSLAUNCH=/usr/bin/dbus-launch
 
 if has_option use-session-dbus; then
-  if [ -x "$DBUSLAUNCH" ]; then
+  if [ -z "$DBUS_SESSION_BUS_ADDRESS" ] && [ -x "$DBUSLAUNCH" ]; then
     STARTDBUS=yes
   fi
 fi
diff -Nru dbus-1.9.20/debian/changelog dbus-1.9.20/debian/changelog
--- dbus-1.9.20/debian/changelog	2015-08-18 14:24:22.000000000 +0000
+++ dbus-1.9.20/debian/changelog	2015-08-18 15:13:55.000000000 +0000
@@ -1,4 +1,4 @@
-dbus (1.9.20-1ubuntu1~ppa1) wily; urgency=medium
+dbus (1.9.20-1ubuntu1~ppa2) wily; urgency=medium
 
   * Merge with Debian (LP: #1477086), remaining changes:
     - Add upstart jobs; Upstart is still supported for the system init.
@@ -20,10 +20,6 @@
       with aptdaemon and large transactions. These problems seem to no longer
       exists, so we will try to run without an increased limit.
     + All other changes merged in Debian.
-    + debian/75dbus_dbus-launch: We now upload DBUS_SESSION_BUS_ADDRESS into
-      an already running dbus, which will (now) cause an attempt to spawn a
-      second D-Bus not to do so. So no need to check for
-      DBUS_SESSION_BUS_ADDRESS here.
 
  -- Iain Lane <iain.lane@canonical.com>  Tue, 18 Aug 2015 15:19:06 +0100