ServiceNotFoundException with non-existent service "plugin.manager.config_entity_migration"

Using 8.x-4.x-dev and 4.0-beta1 (currently the same commit ID as of posting this issue), I'm getting this PHP error:

Symfony\Component\DependencyInjection\Exception\ServiceNotFoundException: You have requested a non-existent service "plugin.manager.config_entity_migration". in Drupal\Component\DependencyInjection\Container->get() (line 157 of /var/www/build/html/core/lib/Drupal/Component/DependencyInjection/Container.php).

Git-bisecting my way backwards, I can pinpoint the introduction of this error to commit 5d12af3d39bb6f6483d19cebbfea1085d2bac8e8, which was for issue #2752335 Properly integrate configuration-entity-based migrations with the core plugin manager. This happens on a fresh rebuild of my dev environment and enabling key migration modules (core Migrate, Migrate UI, Migrate Tools, Migrate Plus) and still persists if I try enabling others (Migrate Drupal/Migrate Drupal UI, Wordpress Migrate/Wordpress Migrate UI, Migrate Example)

I'm using Drupal 8.3.2, and have been able to reproduce this with a custom migration and one created using Wordpress Migration. These migrations work in previous versions of Migrate Plus prior to #2752335. I'm using Migrate Tools 4.0-beta1 as well (using composer require to keep everything version-synced).

Let me know if there's other useful information I can provide, or things I can test.