新增：插件管理器分支选择功能

autoload/tui/core/plug.vim

@@ -89,6 +89,10 @@ def Parse(plug_id: string, plug_options: dict<any> = {}): dict<any>
     # path: string
     const plug_path = tui#util#path#Join(tui#core#cached#Get('tui.plug.home'), split(plug_id, '/')[-1])
     plug_info['path'] = plug_path
+    # branch
+    if has_key(plug_options, 'branch') && !empty(plug_options['branch'])
+        plug_info['branch'] = plug_options['branch']
+    endif
     # enabled: bool / func
     var plug_enabled = v:true
     if has_key(plug_options, 'enabled')
@@ -174,6 +178,9 @@ export def Install()
                 var plug_info = tui_plug_registed[plug_id]
                 if !isdirectory(plug_info['path'])
                     var cmds = 'git clone https://github.com/' .. plug_id .. ' ' .. plug_info['path']
+                    if has_key(plug_info, 'branch') && !empty(plug_info['branch'])
+                        cmds = 'git clone -b ' .. plug_info['branch'] .. ' https://github.com/' .. plug_id .. ' ' .. plug_info['path']
+                    endif
                     echo "executing " .. cmds
                     system(cmds)
                     echo "install success"