Dependency loop via sockets.target

basic.target waits for dbus.socket (via sockets.target) AND dbus.socket waits for basic.target, too, delaying dbus-daemon startup. At some point a timeout happens, dbus is started and all queued services try to start registering to the bus at the same time.

All services registering at the same time, seems to be triggering bugs like this more often: https://bugs.launchpad.net/ubuntu/+source/dbus/+bug/1871538/

This happens since Hirsute (dbus 1.12.20-1ubuntu3), where the following delta was added:

Index: dbus-1.12.20/bus/dbus.socket.in
===================================================================
--- dbus-1.12.20.orig/bus/dbus.socket.in
+++ dbus-1.12.20/bus/dbus.socket.in
@@ -1,5 +1,9 @@
 [Unit]
 Description=D-Bus System Message Bus Socket
+# Do not stop on shutdown
+DefaultDependencies=no
+Wants=sysinit.target
+After=sysinit.target basic.target

 [Socket]
 ListenStream=@DBUS_SYSTEM_SOCKET@

It leads to deadlock situations like this:
09:23:59.276245 systemd[1]: basic.target: starting held back, waiting for: sockets.target
09:23:59.276438 systemd[1]: dbus.socket: starting held back, waiting for: basic.target
09:23:59.304393 systemd[1]: dbus.service: starting held back, waiting for: dbus.socket