That's the command to extend wait time for Conquest maps. If you change the value before someone joins a team, it gets changed nicely and starts from the new value. If you try to change it after the countdown began, it won't change, unlike the Classic wait time command.
Wasn't the work around to this to update it higher than the original value? Like if you wanted say 2 minute wait but wanted to extended an extra 2 minutes you had to put in 4 minutes? Because the value doesn't reset, but it would extend higher. Unless we are talking about something else.
I did the change and stashed it away for now; it should work the exact same way as emp_sv_vote_commander time does next patch.