Infield Fly or Intentionally Dropped Ball?

 
R2 is on second base, R1 is on first base, and there is one out. The batter bunts the ball high into the air between the pitcher's mound and home plate. As the pitcher is about the catch the ball, he sees that R2 and R1 are remaining at their base. Just as the pitcher is about to catch the bunt, he separates his hands and the ball falls to the ground untouched. The pitcher picks up the ball and throws to third base to start a 1-5-4 double play. 

The offensive coach thinks that this is either an infield fly or an intentionally dropped ball, but certainly not a double play. What do the umpires do?

Call
An infield fly is a fair fly -- but does not include a line drive nor an attempted bunt (NF 2-19), so the infield fly does not apply in this case.
 
The batter is not out if an infielder permits a fair fly, fair line drive, or fair bunt to drop untouched to the ground (NF 8-4-1c1), so the intentionally drop penalties do not apply in this case.
 
Without the infield fly or international drop, this is just an infield "ground ball", which the defense has turned into a 1-5-4 double play. The inning is over in the situation below.