That "final" Windows 7 update rolled out with a minor bug. It only affected a very few users but forced a new "final" update to prevent a situation where Windows 7 users would need to pay to fix the glitch in Wallpapers that was introduced the original final update.
From TheVerge: [theverge.com...]

... an embarrassing bug, introduced just as Microsoft was supposed to stop supporting Windows 7. It also left Microsoft with the dilemma of introducing an obvious bug that customers would then have to pay to get fixed.