Question about pbulk and build dependencies

[John Marino <netbsd%marino.st@localhost>]

pkg-config was just updated from 0.25 to 0.27.
Theoretically, this shouldn't affect pbulk packages at all assuming no 
packages requires a version greater than 0.25.

However, I'm wondering if pbulk keys off of date stamp rather than 
version?  Will it build pkg-config, and then every package that needs 
pkg-config to build will also get built, and thus cascading?

In short, would touching any file in something like pkg-config cause 
just about every package to get rebuilt in pbulk assuming this is the 
only change from the previous run?

John