filemanager shows broken symlinks

https://github.com/jupyter/notebook/blob/ae011a179742a7f4348476beb27faf375b1884fe/notebook/services/contents/filemanager.py#L311

is using: `os.lstat`
Equivalent to stat(path, follow_symlinks=False).

the comment following that block of code says:
`# skip over broken symlinks in listing`

perhaps in the past the comment was true... however as it is now the file listing shows broken links.
The broken links are an issue for our university because we have symlinks to extra home dirs
that wont resolve... when users click them they get a `404 error page`

can this be changed to use `os.stat` so broken symlinks are hidden, or could a config option be added to hide broken symlinks... or perhaps color code them red.

thanks