It's always worked without Drang since year 1... Not only that, but the perk says, "Kills with this weapon fill the magazine of the [b][i]equipped Energy weapon[/i][/b] from reserves." Also, Jade Rabbit is exceptionally good in PVP (no arguments here), but in PVE it was never as good for being an exotic weapon for most people, but it was still good imo. However its perk no longer refills the guns mag making it seem like just an ordinary scout in PVE. It really needs to get fixed.