bug#50732: 28.0.50; project-find-dir: blank line in fido-vertical-mode

[Juri Linkov]

>>> But should it be changed? It seems, while "" is a valid choice (which
>>> leads to visiting the root directory), without it in the completions set
>>> fido-vertical-mode doesn't easily allow you to select such
>>> option. Whereas the default completion UI does.
>> Interesting, it seems to be just a matter of how it looks with a vertical
>> UI then. With the default completion a blank makes more sense to my eyes.
>> However, this option leads to the root directory just like C-x p D does,
>> IIUC. I guess I could live without the blank line since there is already
>> a key binding for a Dired buffer in the project root.
>
> That also makes a certain amount of sense.
>
> What do other people think?

Please don't change project-find-dir, it has no problem.
The problem is in fido-vertical-mode.  It should display
an empty string with some visual indication, for example:

  <empty>
  dir1
  dir2