Truljin @ Twitch
Quote from DemonStrate:
46:55 is around where he discovers that any dialog will skip mission dialog. He talks to someone in the tower to skip Jade's dialog. Then he uses Gassed Up to meet Jade at the boxcar. That's the first useful Side Mission Warp in his run. He does one before that, but it wastes time.
Skipping mission dialogue with someones elses is already known though, just look at The Old Town when you have to meet Jade, that random guy always interrupt her talking and will instantly trigger the next part of the mission.
I guess it works on demand now by talking to any npc while one is running.