Revert "style: For Tree/TreeSelect with showLine set to true, when the top no…" (#2613)

packages/semi-ui/tree/_story/tree.stories.jsx

@@ -207,17 +207,6 @@ const treeDataWithIcon = [
   },
 ];
 
-const OneLevelData = [
-  {
-    label: '亚洲',
-    key: 'yazhou',
-  },
-  {
-    label: '北美洲',
-    key: 'beimeizhou',
-  },
-]
-
 let opts = {
   content: 'Hi, Bytedance dance dance',
   duration: 3,
@@ -3089,14 +3078,6 @@ export const ShowLine = () => {
       defaultExpandAll
       disableStrictly
     />
-    <>单选，单层节点</>
-    <Tree
-      showLine={showLine}
-      treeData={OneLevelData}
-      // value="meiguo"
-      defaultExpandAll
-      onChange={(...args) => console.log(args)}
-    />
   </div>
   )
 }

packages/semi-ui/tree/treeNode.tsx

@@ -203,7 +203,7 @@ export default class TreeNode extends PureComponent<TreeNodeProps, TreeNodeState
 
     renderArrow() {
         const showIcon = !this.isLeaf();
-        const { loading, expanded, showLine, level } = this.props;
+        const { loading, expanded, showLine } = this.props;
         if (loading) {
             return <Spin wrapperClassName={`${prefixcls}-spin-icon`} />;
         }
@@ -218,8 +218,7 @@ export default class TreeNode extends PureComponent<TreeNodeProps, TreeNodeState
                 />
             );
         }
-        // when leaf node 's level is 0, no switcher
-        if (showLine && level) {
+        if (showLine) {
             return this.renderSwitcher();
         }
         return (