Pop-Up on a Bunt Attempt

 
With no outs, full count, and a runner on 1st base (R1), R1 is stealing on the pitch. Surprisingly, the batter (B1) bunts. The ball is popped high into the air halfway down the third base line. Both the catcher and pitcher dive for the ball, but the ball lands fair and rolls (untouched) just into foul territory, where it stops. R1 is now standing on 2nd base while B1 is on 1st base.
 
Are there any actions for the umpires?
 
Call
The batted ball described below is foul, since it settled untouched in foul territory between home plate and third base (NF 2-16-1a). A batter that bunts foul with two strikes is out (NF 2-8 and 7-4-1e). The ball is dead, so R1 must return to first base.