Weird character sequence appears if run from ~/.vim folder

Nobody has claimed this yet.

This does not happen so far in any other folder... If I run ``:Tree`` from ~/.vim folder, then instead of clean box drawing lines, I see the following weird character sequence. This happens even if vim-tree is the only plugin I load, and happens with both vim and neovim.

```
├── UltiSnips/
│  ├── mail.snippets
│  └── tex.snippets
├── after/
│  └── ftplugin/
│  ├── mail.vim
│  ├── qf.vim
│  ├── rust.vim
│  ├── tex.vim
│  └── vimwiki.vim
├── autoload/
│  ├── AnsiEsc.vim
│  ├── plug.vim
│  └── plug.vim.old
├── bundle/
│  ├── autoload/
│  │  └── vimwiki/
│  │  ├── base.vim
```

And here's the screenshot:


Relevant information:
```
Vim 8.2 patches 1-2890 ARM64
NeoVim v0.5.0-dev+nightly-356-gb28d458f8 ARM64
macOS BigSur 11.4 ARM64
$TERM xterm-256color
```

Start with the :Tree entry point and reproduce the output from ~/.vim in both Vim and Neovim, then compare it with running from another folder. Use the reported macOS, ARM64, terminal, and version details while checking that box-drawing characters render correctly; done means the clean tree output is restored in ~/.vim.

Written by the indexing model from the issue text.