This question showed up in the feed marked modified by community. It's in active right now. I looked at it and can't figure what the bot modified to get it to show up. Can someone tell me how I can figure this out in the future?
Community is designed to kick up unanswered questions (positive question score, no positive-score answers) every now and again to bring it back to our attention.
It used to be very common to see this kind of behavior before our massive cleanup drive last month, so it's little surprise that we don't see such modifications as often as before.
I don't think "Community" has to really modify anything. I would bet (and this is just a guess) that the system uses the "last modified date" as to whether the question is active. Community wouldn't have to change anything outwardly to update this field in the database. In doing so it will bring the question to the foreground and out of the shadows.
This is just my take on it, but would bet it's something along these lines.