bug#29473: 25.3; 'background-mode is 'light on console with black background

[Tim Landscheidt]

In newsticker tree view on a Linux console with black back-
ground (both KDE's konsole application and "native" console
(Alt-Ctrl-F2), all under Fedora), titles of folders with no
items are displayed black on black, i. e. they are still
copyable, but not visible.  Changing the selected title with
RET highlights that one correctly and hides the previous one
if it has 0 items, suggesting that the face
newsticker-treeview-face is at fault.

Changing (:foreground "black") to (:foreground "yellow") in
newsticker-treeview-face's (background light) case makes the
titles visible and indeed
(frame-parameter nil 'background-mode) returns 'light.  This
also happens with Emacs' current master branch.

After glancing at the manual, I'm unclear whether:

1. Emacs should set 'background-mode correctly by itself
   (and thus there is an error in the detection mechanism),

2. it is my duty to explicitly set background-mode (via
   initial-frame-alist?) when using Emacs on a console, or

3. newsticker should use a different technique (I've used
   Emacs on consoles many times and do not remember running
   into similar problems with other parts of Emacs).