After rescuing the deputy in Primm, I completed the quest to find a new sheriff by getting the ex-sheriff in the NCR prison to do the job.

But when I walk by random NPCs they remark about how Primm sold out to the NCR for protection. However, when I talked to named NPCs, they act like I installed the NCR prisoner as sheriff.

I guess there must be some bug in npcs reading that quest script?

If you have to put a spoiler warning in the title, you can bet it belongs in the spoiler section. Moving it there now.