Neos\Neos\Setup\Step\SiteImportStep::deactivateOtherSitePackages PHP Method

    protected function deactivateOtherSitePackages($packageKey)
    {
        $sitePackagesToDeactivate = $this->packageManager->getFilteredPackages('active', null, 'neos-site');
        $deactivatedSitePackages = array();
        foreach ($sitePackagesToDeactivate as $sitePackageToDeactivate) {
            if ($sitePackageToDeactivate->getPackageKey() !== $packageKey) {
                $this->packageManager->deactivatePackage($sitePackageToDeactivate->getPackageKey());
                $deactivatedSitePackages[] = $sitePackageToDeactivate->getPackageKey();
            }
        }
        if (count($deactivatedSitePackages) >= 1) {
            $this->flashMessageContainer->addMessage(new Message(sprintf('The existing Site Packages "%s" were deactivated, in order to prevent interactions with the newly created package "%s".', implode(', ', $deactivatedSitePackages), $packageKey)));
        }
    }