Nesting seems to get funkified from time-to-time. IceWeasel (Mozilla?): 38.8.0
Here's a particularly long example. The proper-nesting begins at the bottom of the third image.
Indeed, it's very hard to see, here... but when scrolling on a "short" window, it's very noticeable, as the rightward-shift typically indicates whether you're still viewing the same update, or whether there's a new one... here's the first image (where the nesting problem begins) repeated:
It's very hard to see in the subsequent images, but the nesting continues for several screens, including an update from an entirely different user on a completely unrelated project:
Here's where the feed begins nesting properly, again: