Neos\Flow\Core\Migrations\Manager::hasMigrationApplied PHP Method

    protected function hasMigrationApplied(AbstractMigration $migration)
    {
        // if the "applied-flow-migrations" section doesn't exist, we fall back to checking the git log for applied migrations for backwards compatibility
        if (!isset($this->currentPackageData['composerManifest']['extra']['applied-flow-migrations'])) {
            return Git::logContains($this->currentPackageData['path'], 'Migration: ' . $migration->getIdentifier());
        }
        return in_array($migration->getIdentifier(), $this->currentPackageData['composerManifest']['extra']['applied-flow-migrations']);
    }