Checking if it's non-empty and not a directory gets us quite far, but
not all the way. While a working symlink would trigger the earlier
checks, a broken symlink does not.
This commit fixes the special case where ~/.local/share/nvim already
exists but is a broken symlink. Thus, it fixes the following error on
startup:
E739: Cannot create directory /home/samuel/.local/share/nvim: file
already exists
(cherry picked from commit a6051e68a3)
8a85eb7a21
