Bad gameloop values in replays from loaded/saved games

If you save a game, and then load it and play it, the resulting replay file has events with bad _gameloop values (e.g. 4294970998). They are bad in that they are huge numbers with some very high-order bits set.

Example replay: https://dl.dropboxusercontent.com/u/556553/put_things_here/s2protocol_issue.SC2Replay

Demonstration of the problem: https://gist.github.com/dsjoerg/c75ae52ce8099b430ee5

Perhaps the solution is to simply mask out the higher-order bits of the gameloop? That's what I did in sc2reader: https://github.com/GraylinKim/sc2reader/commit/c860d8e23d6fbd3a9258deff9fcbe8796da6c900