It's brilliant actually. They support Trump (like they did before) and by supporting Sanders, who (I don't think can win) will be hurt by the association... Russia further supports Trump. Classic win-win for Putin.
HAHAHHA...You do realize how ridiculous you sound, right? When Russsia purportedly supports Trump its because Trump is a Russian schill. When Russia supports Sanders, its because they want to support Trump who is still a Russian schill. HAHAHAHA
It doesn't matter what happens, because morons will always say "Russia has Trump in their back pocket".
Well, since they supported him in 2016 wouldn't that make sense. Besides, Trump doesn't have to be a shill to be useful, just an idiot. The more nationalistic, and thus divided, Russia's enemies are the better for them, i.e. Brexit.