I donated thousands of hours to the Sanders campaign, was closely involved with Coders for Sanders and FeelTheBern.org, having authored the section on abortion among other things such as curating http://j.mp/berniewouldawon
I never observed authentic Sanders volunteers engaging in this kind of harassment, but there were plenty of trolls who did so in order to discredit us. The trolls were incredibly successful. When Bernie himself was giving interviews asking his supporters to reach out to their local superdelegates, the organizational heiarchy in charge of volunteers was saying the opposite because trolls had contacted them and told them that Sanders supporters were threatening physical harm to the superdelegates.
I’m sorry to the people who have had this happen to them, but as far as I can tell, it isn’t actual Bernie supporters doing this.