Screenshot taken straight from the official blog post:
You see, they wanted to add a feature where you could “watch” a repository.
Only … due to some weak design (or perhaps: technology-led) decisions in the past, they already had a feature with this name, which didn’t really do what it claimed to do. Rather than fix it … they added a meaningless button that does what the existing button (Watch) pretends to do. So now, when you want to watch a project, you must NOT CLICK the Watch button, with its excellent icon, but instead the “burning lump of gas” button. Um.
Here’s a hint: if you’re designing a UI, and at any point you decide:
“STARS! Starring items is the answer!”
…and the question was anything other than “how do we Rate items?”, then: you’re wrong. Try again.
(PS: they’ve also fixed the extremely annoying long-time bug that people could raise Issues, or Comment, on your repository – but you’d never find out, again because of technical decisions / implementation issues on their system. Apparently alll fixed now. Yay!)