curzone reality check and teardown changes to use the RIGHT zone

@@ -872,10 +872,11 @@
 
         avl_index_t             where;  /* used for avl_find()/avl_insert() */
 
         ASSERT(cr != NULL);
 
+        ASSERT3P(curzone, ==, exi->exi_zone);
         nag = zone_getspecific(nfsauth_zone_key, curzone);
 
         /*
          * Now check whether this client already
          * has an entry for this flavor in the cache