[GAMEPLAY] Won a 3v3 ranked by surrendering

I played a ranked 3v3 with some friends, we were clearly losing and decided to surrender, when surrendering we were greeted with the victory screen and gained LP, link to the game: http://matchhistory.euw.leagueoflegends.com/en/#match-details/EUW1/2830772908/220418736 That is the full description of the bug, this was on EUW btw and only happened once so far.