Commit fca8adb0 has the logic backwards, it uses 800x600 or smaller instead of 800x600 or larger.
This is related to bug 750764 with dual displays. It was using the full size of both displays as the windowsize, which isn't really what we want either. It would be better to pick the size of the display anaconda is being shown on, or pick the size of the smallest connected display, falling back to 800x600 if neither of those can be reliably discovered.
whatever this means, it's done already, according to bcl, and bug should be closed.