We've included Power Pack as a default extension in both the Docker

images and in Review Board for a while now. We're now including it as an

install-time dependency as well.
This is required in order to ease product activation and tier selection

without having to go install Power Pack manually.
Going forward, we will be more closely aligning the versions of

Review Board and Power Pack so that the versions don't risk drifting

much and to enable more rapid development of features. We're starting

that by requiring Power Pack 6 in Review Board 8.
New constants have been added to define the version of the

rbintegrations and ReviewBoardPowerPack packages, just like with

Django and Djblets, so it's easier for us to alter these versions.
The dependencies lists have been split into a base set of dependencies

common to all targets, into a set of package dependencies containing

the package-only dependencies (for wheels), and into editable

dependencies (just the base set). This along with buildthings 1.1 is

needed to get the package-only dependencies into the package metadata.

Set up an editable install and build sdists and wheels.
Neither the editable install nor any isolated build environment

included Power Pack or rbintegrations.
The wheel listed both in the package metadata.
The sdist also listed both in the legacy .egg-info/PKG-INFO.