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()
calls:initvariable("g:NERDTreeDirArrowExpandable","?~V?")
calls:initvariable("g:NERDTreeDirArrowCollapsible","?~V?")
else
calls:initvariable("g:NERDTreeDirArrowExpandable","+")
calls:initvariable("g:NERDTreeDirArrowCollapsible","~")
endif

改成：

"if!nerdtree#runningWindows()&&!nerdtree#runningCygwin()
"calls:initvariable("g:NERDTreeDirArrowExpandable","?~V?")
"calls:initvariable("g:NERDTreeDirArrowCollapsible","?~V?")
"else
calls:initvariable("g:NERDTreeDirArrowExpandable","~")
"endif