Hello,

When the icomplete-vertical-mode is on, pressing TAB to complete a
single option using find-file C-x C-f behaves as expected but pressing
TAB to select one of two options pops two completions windows and is
unexpected.

To retrace steps,

 1. open "emacs -Q"
 2. M-x icomplete-vertical-mode
 3. navigate with TAB completions after find-file C-x C-f

Say, I want to open the following using find-file C-x C-f

  /usr/src/external/gpl3/gcc/dist/gcc/configure

The directory /usr/src/external has two subdirectories gpl2 and gpl3.

at the point /usr/src/ex TAB completes the path to /usr/src/external/

at the point /usr/src/external/gp TAB completes the path to /usr/src/external/gpl

at the point /usr/src/external/gpl

C-n or C-p will move the highlight between gpl2 or gpl3 (See A)

pressing TAB pops a second *Completions* window (See B)

Expected behavior is for TAB to pick the highlighted directory and continue with path to file selection

=> http://sdf.org/~van.ly/img/emacs-30-0-91-pretest-icomplete-vertical-mode-buffer-A.jpeg A
=> http://sdf.org/~van.ly/img/emacs-30-0-91-pretest-icomplete-vertical-mode-buffer-B.jpeg B