Vim的NERDTree插件无法打开目录，显示�~V�

在ubuntu的docker镜像中，给vim安装了NERDTree插件，但是本来目录左侧应该显示“+”，但是变成了“�~V�”，而且无法打开目录。

解决方案：

编辑NERD_tree.vim文件，把

if !nerdtree#runningWindows() && !nerdtree#runningCygwin()                                  
    call s:initVariable("g:NERDTreeDirArrowExpandable", "�~V�")                             
    call s:initVariable("g:NERDTreeDirArrowCollapsible", "�~V�")                            
else                                                                                        
    call s:initVariable("g:NERDTreeDirArrowExpandable", "+")                                
    call s:initVariable("g:NERDTreeDirArrowCollapsible", "~")                               
endif                   

改成：

"if !nerdtree#runningWindows() && !nerdtree#runningCygwin()                                 
"    call s:initVariable("g:NERDTreeDirArrowExpandable", "�~V�")                            
"    call s:initVariable("g:NERDTreeDirArrowCollapsible", "�~V�")                           
"else                                                                                       
    call s:initVariable("g:NERDTreeDirArrowExpandable", "+")                                
    call s:initVariable("g:NERDTreeDirArrowCollapsible", "~")                               
"endif