Punting post-6.1, nobody else is complaining about this.

I believe that this should fix it:

Index: app/setup.c
===============================================================
====
--- app/setup.c (revision 1162)
+++ app/setup.c (working copy)
@@ -1703,6 +1703,10 @@
 
                config_get_slimserver_name(slimserver_name);
                slimserver_address = config_get_slimserver_address();
+
+               if (strlen(slimserver_name) == 0 && slimserver_address) {
+                       ip_string(slimserver_name, slimserver_address, 0);
+               }
 
                network_slimserver_add(slimserver_name, slimserver_address);
        }

Hm, I can't reproduce this now, no wonder nobody's complaining.