In the plugin registers with the debug framework at open time, the

sudo front-end will now set the default debug instance appropriately
before calling into the plugin.  This means the plugin no longer needs
to do the sudo_debug_set_default_instance() dance.

src/sudo_plugin_int.h

@@ -87,6 +87,7 @@ struct plugin_container {
     const char *path;
     char * const *options;
     void *handle;
+    int debug_instance;
     union {
 	struct generic_plugin *generic;
 	struct policy_plugin *policy;