修正一对一嵌套关联数组定义的问题

library/think/db/Query.php

@@ -1902,6 +1902,9 @@ class Query
                 $closure    = $relation;
                 $relation   = $key;
                 $with[$key] = $key;
+            } elseif (is_array($relation)) {
+                $subRelation = $relation;
+                $relation    = $key;
             } elseif (is_string($relation) && strpos($relation, '.')) {
                 $with[$key]                   = $relation;
                 list($relation, $subRelation) = explode('.', $relation, 2);