Going up one dir in NERDTree keeping the old root open, together with all its open children, recursively

Question

I do this,

$ tree
.
├── dir1
│   ├── dir11
│   │   └── hello
│   └── dir12
│       └── hello
└── dir2
    ├── dir21
    │   └── hello
    └── dir22
        └── hello
$ cd dir1/dir11
$ vim

then I open NERDTree, and see it shows

  [  ]hello

then I press Shift+U twice, and NERDTree shows this:

▾ [  ]dir1/
  ▸ [  ]dir11/
  ▸ [  ]dir12/
▸ [  ]dir2/

whereas I expected this:

▾ [  ]dir1/
  ▾ [  ]dir11/
      [  ]hello
  ▸ [  ]dir12/
▸ [  ]dir2/

Unless someone tells me it has always worked the former way, I'm pretty sure I relied on it working the latter way.

EDIT:

When I'm in the NERDTree window, :map U gives back this:

n  U           *@:call nerdtree#ui_glue#invokeKeyMap("U")<CR>

Answer 1

As suggested by BLayer in the comments, the problem comes from the settings.

However, it's not a NERDTree setting, but a vim-devicons setting which breaks the U command of NERDTree!

Indeed, this is the culprit in my ~/.vimrc:

let g:DevIconsEnableFoldersOpenClose = 1

This setting is meant to use a special symbol for open folder, and it works, in that sense. However I have to comment it to take advantage of NERDTree's U mapping.

I've opened an issue.