Mike Hearn, formerly with Google, calls a recent report on Twitter bots promoting Brexit "deliberate lying, or if you like, fake news."
Without having looked into it further than reading his response, I'm doubtful about his doubtfulness. I suspect the kind of bots he was trying to identify were a different variety. He says he never saw "cyborg" accounts. He doesn't mention that Russia is known to employ people for social media propaganda.