To close this off, it looks like Magento fixed the problem again. It works again with no changes made on my part.
I have the same problem with Magento 2.2 when installing a language pack with composer.
magento@me-dev:/var/www/html/me$ composer require magento2translations/language_zh_cn:dev-master ./composer.json has been updated Loading composer repositories with package information Updating dependencies (including require-dev) Your requirements could not be resolved to an installable set of packages. Problem 1 - magento/framework 100.0.18 requires php ~5.5.0|~5.6.0|~7.0.0 -> your PHP version (7.1.11) does not satisfy that requirement. - magento/framework 100.1.9 requires php ~5.6.5|7.0.2|7.0.4|~7.0.6 -> your PHP version (7.1.11) does not satisfy that requirement. - magento/framework 100.1.8 requires php ~5.6.5|7.0.2|7.0.4|~7.0.6 -> your PHP version (7.1.11) does not satisfy that requirement. - magento/framework 100.0.17 requires php ~5.5.0|~5.6.0|~7.0.0 -> your PHP version (7.1.11) does not satisfy that requirement. - magento/framework 100.0.16 requires php ~5.5.0|~5.6.0|~7.0.0 -> your PHP version (7.1.11) does not satisfy that requirement. - magento/framework 100.1.7 requires php ~5.6.5|7.0.2|7.0.4|~7.0.6 -> your PHP version (7.1.11) does not satisfy that requirement. - magento/framework 100.1.6 requires php ~5.6.5|7.0.2|7.0.4|~7.0.6 -> your PHP version (7.1.11) does not satisfy that requirement. - magento/framework 100.0.15 requires php ~5.5.0|~5.6.0|~7.0.0 -> your PHP version (7.1.11) does not satisfy that requirement. - magento/framework 100.1.5 requires php ~5.6.5|7.0.2|7.0.4|~7.0.6 -> your PHP version (7.1.11) does not satisfy that requirement. - magento/framework 100.0.14 requires php ~5.5.0|~5.6.0|~7.0.0 -> your PHP version (7.1.11) does not satisfy that requirement. - magento/framework 100.1.4 requires php ~5.6.5|7.0.2|7.0.4|~7.0.6 -> your PHP version (7.1.11) does not satisfy that requirement. - magento/framework 100.0.13 requires php ~5.5.0|~5.6.0|~7.0.0 -> your PHP version (7.1.11) does not satisfy that requirement. - magento/framework 100.1.3 requires php ~5.6.5|7.0.2|7.0.4|~7.0.6 -> your PHP version (7.1.11) does not satisfy that requirement. - magento/framework 100.1.2 requires php ~5.6.5|7.0.2|7.0.4|~7.0.6 -> your PHP version (7.1.11) does not satisfy that requirement. - magento/framework 100.0.12 requires php ~5.5.0|~5.6.0|~7.0.0 -> your PHP version (7.1.11) does not satisfy that requirement. - magento/framework 100.1.1 requires php ~5.6.0|7.0.2|~7.0.6 -> your PHP version (7.1.11) does not satisfy that requirement. - magento/framework 100.0.11 requires php ~5.5.0|~5.6.0|~7.0.0 -> your PHP version (7.1.11) does not satisfy that requirement. - magento/framework 100.0.10 requires php ~5.5.0|~5.6.0|~7.0.0 -> your PHP version (7.1.11) does not satisfy that requirement. - magento/framework 100.1.0 requires php ~5.6.0|7.0.2|~7.0.6 -> your PHP version (7.1.11) does not satisfy that requirement. - magento/framework 100.0.9 requires php ~5.5.0|~5.6.0|~7.0.0 -> your PHP version (7.1.11) does not satisfy that requirement. - magento/framework 100.0.8 requires php ~5.5.0|~5.6.0|~7.0.0 -> your PHP version (7.1.11) does not satisfy that requirement. - magento/framework 100.0.7 requires php ~5.5.0|~5.6.0|~7.0.0 -> your PHP version (7.1.11) does not satisfy that requirement. - magento/framework 100.0.6 requires php ~5.5.0|~5.6.0|~7.0.0 -> your PHP version (7.1.11) does not satisfy that requirement. - magento/framework 100.0.5 requires php ~5.5.0|~5.6.0|~7.0.0 -> your PHP version (7.1.11) does not satisfy that requirement. - magento/framework 100.0.4 requires php ~5.5.0|~5.6.0|~7.0.0 -> your PHP version (7.1.11) does not satisfy that requirement. - magento/framework 100.0.3 requires php ~5.5.0|~5.6.0|~7.0.0 -> your PHP version (7.1.11) does not satisfy that requirement. - magento/framework 100.0.2 requires php ~5.5.0|~5.6.0|~7.0.0 -> your PHP version (7.1.11) does not satisfy that requirement. - magento2translations/language_zh_cn dev-master requires magento/framework ~100.0 -> satisfiable by magento/framework[100.0.2, 100.0.3, 100.0.4, 100.0.5, 100.0.6, 100.0.7, 100.0.8, 100.0.9, 100.1.0, 100.0.10, 100.0.11, 100.1.1, 100.0.12, 100.1.2, 100.1.3, 100.0.13, 100.1.4, 100.0.14, 100.1.5, 100.0.15, 100.1.6, 100.1.7, 100.0.16, 100.0.17, 100.1.8, 100.1.9, 100.0.18]. - Installation request for magento2translations/language_zh_cn dev-master -> satisfiable by magento2translations/language_zh_cn[dev-master]. Installation failed, reverting ./composer.json to its original content.