Make f-directories optionally ignore permission errors

[mattiasb]

Hi!

I constructed the following little helper function to help me fill up my projectile index just now:

(defun my/find-git-projects (dir)
  "Find all git projects under DIR."
  (mapcar #'f-dirname
          (f-directories "~/Documents/"
                         (lambda () (equal (f-filename dir) ".git"))
                         t)))

Unfortunately I get the following error:

f--collect-entries: Opening directory: Permission denied, c:/Users/mattias.bengtsson/AppData/Local/Application Data

Would it be possible to teach f-directories to optionally ignore directories it can't reach due to permissions instead of erroring out?

[rejeep]

No, I think this is basically the same issue as #73

[mattiasb]

Indeed it is.