[yocto] kernel change detection for packages that depend on kernel version?

[Benjamin Fleming]

I'm running into an issue where the branch for my kernel received some new commits, changing what the kernel version string looks like. When I rebuilt my system (bitbake my-image) the kernel was rebuilt (I believe at some point I probably also ran bitbake virtual/kernel -c clean), however several OOT kernel module packages were not rebuilt (one of our modules, as well as lttng-modules). In addition, I have the kernel-devsrc package included in my TOOLCHAIN_TARGET_TASK, and running "... -c populate_sdk" seems to have built an SDK containing the old kernel source. Cleaning those recipes allowed them to rebuild properly, but it seems like rebuilding should have happened automatically...
My image recipe looks like this (very abbreviated):
inherit core-image
IMAGE_INSTALL_append = " packagegroup-core-boot kernel-modules my-oot-module"
IMAGE_FEATURES += "package-management"
TOOLCHAIN_TARGET_TASK_append = " kernel-devsrc"

This brings me to my questions:

1. How do recipes that depend on the kernel headers tell when they need to rebuild? Is there something wrong with my kernel recipe? (for reference, I'm using this one: https://github.com/kraj/meta-altera/blob/master/recipes-kernel/linux/linux-altera-ltsi-rt_3.10.bb)

2. Why didn't kernel-devsrc rebuild after the kernel changed?

3. How do I clean the populate_sdk output? Will do_clean clean the populate_sdk output as well? I know I can force it to rerun with "... -f -c populate_sdk"

Thanks for your help,
Ben