I think I've realized that the "bootstrap kit" and at least pbulk
should be reinstalled between pkgsrc branch installs. To me
there's an impediment to doing this, in that any and all
customizations to pbulk.conf will get lost in such an update
and/or requies a manual step to preserve and reinstate the local
customizations..
How, then, about this modification? If /etc/pbulk.conf exists,
source it from the default pbulk.conf file? That way, the
customizations can be put in a file which is untouched by a pbulk
reinstall. (In my case, this happesn in a chroot, of course.)