Goto the *scratch* buffer, and perform

M-: (ls-lisp-insert-directory "/tmp/" '(?F) nil nil nil)

Move the cursor into the string /tmp/, and perform

M-x describe-char

There is no text property 'dired-filename, as it should.

The following patch seems to cure the problem. Run the same test, you
will see the text property 'dired-filename.