Currently replaying Fallout: New Vegas and "the distinctive cigarette butt" that one could pickup near the grave used to start a quest but now nothing happens, did this break get removed in a official patch, with the unofficial patch or some other mod?

These along with Benny's Lighter, gained later, allow one to motivate Swank at the Topps to empower you to finish investigating Benny there, armed to the teeth no less. Ends up with Topps as one casino which does not take away weapons.

It doesn't start a quest persay, but if you use that, along with other evidence of Benny betraying house you can collect (as said above), you can use them to convince the tops guy to let you in with your weapons, as well as potentially help you take down Benny with the right speech.

But Yeah, it doesn't start an actual quest, it's just used for an alternate way of completing the first act of the main quest.