Hi maintainers,

   Emacs -Q
   M-x icomplete-mode
   C-x C-f
   C-.

Expected candidate list to rotate once to the left, immediately.
Instead if only rotates if I press C-. two additional times.  This is
because "."  and ".." are still taking part in the rotation under the
hood (but the user doesn't see them, by default, because of
completion-ignored-extensions).

Seems to have been introduced by

   commit 65797b1d75e9f608ffd50fd88be47a854b143bb1
   Author: Drew Adams <drew.adams@oracle.com>
   Date:   Thu Apr 28 19:31:43 2016 +0200
    
       Make icomplete respect `completion-ignored-extensions'
       
       * lisp/icomplete.el (icomplete-completions): Heed
       `completion-ignored-extensions' (bug#12939).

Naive patch attached that seems to fix it for me.

Here's another problem that might be related (should I open a new bug?)

   When using substring completion and navigating deeper in directories
   using successive C-M-i's (sometimes the directories don't make sense)
    
   Try it with:
    
     Emacs -Q
     M-: (add-to-list 'completion-styles 'substring)
     M-x icomplete-mode
     C-x C-f p a t h / t o / e m a c s /
     s r c C-M-i
    
   Expected to see the same as if I had typed "s r c /", instead I see
   "{src | lib-src}"