Around here the banks usually provide a bridge loan, eg, you buy the second house and you're covered till the other one is sold.
But obviously that carries it's own risks and drawbacks.. And i wouldn't recommend it this day and age.. to much funky stuff happening..
But realistically , there's nothing you can do about it, other then trying to get the house sold.
It also helps to not focus to much on this one house... keep looking around for others.. just in case the one goes ,
and in case you find something else that might even be better, you never know.
And go to the range a lot.. that oughta help