Change Default Wallpaper Ubuntu

So, I'm running ubuntu 12.10 with Gnome-Shell (instead of Unity) and GDM as the display manager (as opposed to LightDM), and I have to say, that so far, this is a great setup.

I'm really happy with how smooth Gnome-Shell is now. However, I still have one issue, which has been bugging me. When you first logon, you see the ugly-ass Ubuntu default wallpaper for just an instance before your chosen wallpaper comes up. Also, if you use wally to change your wallpaper, you see the default wallpaper for a second or so when the wallpaper changes.

Well, the fine folks on the #ubuntu-gnome freenode IRC channel explained how to change the default wallpaper:

First, if you take a look at the file:
    /usr/share/glib-2.0/schemas/10_ubuntu-settings.gschema.override

You will find this section:
    [org.gnome.desktop.background]
    show-desktop-icons=true
    picture-uri='file:///usr/share/backgrounds/warty-final-ubuntu.png'

This is what is telling the system the location of the default wallpaper. So you could just modify this section, and then be done.

But if you did that any update that rewrites that file may overwrite your changes.

So this fix will be more resistant to updates:

In the same folder mentioned above, make a new file called:
    30_custom-settings.gschema.override

and put the following text in it:
    [org.gnome.desktop.background]
    picture-uri='file:///usr/share/backgroundsWHATEVERBACKGROUNDYOUWANT'

Two things to note about this:
First, you will want to pick an image in that folder, or put an image in there you want to use.
Second, the file in question can be named whatever you like, but must have a number on it - the higher the number the greater the priority with overridden settings. 

After you have saved the file, run this from the terminal:
    sudo glib-compile-schemas /usr/share/glib-2.0/schemas/

Then logout, and you should see the chosen wallpaper instead of that default one.