0.19.1987 Only first rock chunk slows colonists

[erdrik]

Im not 100% certain this is a bug but I thought Id bring it up just in case.

I tend to have very large dumping stockpiles for rock chunks because I primarily work with stone walls. Occasionally my colonists will place an animal corpse in the rock chunk stockpile(because I forget to fully setup the dumping stockpile or make it multi purpse if I don't have a corpse freezer yet).
I noticed when the cook went to get the corpse to butcher it he was only slowed down by the first rock chunk he walked over in the stockpile, then was walking at normal speed afterwards despite walking over a bunch of other rock chunks within the stockpile.