Review Board 4.0 is the first release to use a version of Django with

the built-in migrations framework, which was incompatible with

evolutions. Django Evolution 2.0 was released to orchestrate new

database installs and upgrades that incorporated both evolutions and

migrations, but it had a flaw that broke new installs on Review Board.
Basically, Django Evolution attempted to install initial migrations

first, then evolutions, and then any remaining migrations. However, the

oauth2_provider app was a bit of a special case in that its initial

migration looks up a model that must be configured in settings by the

project to store project-specific information, and adds a ForeignKey

to it. They require an initial migration for the project's model with a

reverse-dependency, set to run before oauth2_provider's initial

migration.
Django Evolution 2.1 further works around this by allowing evolutions to

specify dependencies and reverse-dependencies at both the app and

evolution levels, and generating the correct order of dependencies based

on that.
We now depend on 2.1 for this functionality, and set the necessary

dependencies in reviewboard.oauth to ensure that our model is created

before oauth2_provider's migration is run, and to ensure that

reviewboard.site is created before reviewboard.oauth (since the

model points to a LocalSite, and reviewboard.site would otherwise be

installed sometime after oauth2_provider in a different transaction.
With this, it's now possible to install or upgrade a Review Board

database on all supported databases.

Successfully created a database on SQLite, MySQL, and Postgres.
Successfully upgraded a Review Board 3.0.19 database to 4.0 on

SQLite, MySQL, and Postgres.
Unit tests pass (aside from a couple that were already failing).