So the Second Public Test of the 8.4 update has been announced. There is really not a very great deal to add (patch notes here). Most usefully is the new matchmaking for 8.4 which can be found here. In particular it how Wargaming is approaching the matchmaking for the Tier V lights. Essentially the “standard” Tier V light matchmaking will be Tier VI-IX, whilst the Crusader, M24 Chaffee, and T-50-2 retain their current matchmaking. The matchmaking for the last two is almost the same for the new standard Tier VI light tank, and presumably as those tank lines are given the same treatment the German line is getting in this patch they will move onto this newer matchmaking.
Otherwise one element of the new update, that was not written into the earlier patch-notes, is we will be able to select which ammunition we wish to load in that thirty second countdown at the start of each match.
Otherwise the notes are mostly a long list of fixes and the like, which are not of much interest to me personally given I do not take part in the public tests.