Merge remote-tracking branch 'upstream/8.x' into kernel

core/CHANGELOG.txt

core/includes/config.inc

core/includes/update.inc

core/lib/Drupal/Core/Config/DatabaseStorage.php

core/lib/Drupal/Core/Config/DrupalConfig.php

core/lib/Drupal/Core/Config/FileStorage.php

core/lib/Drupal/Core/Config/FileStorageException.php

core/lib/Drupal/Core/Config/FileStorageReadException.php

core/lib/Drupal/Core/Config/StorageBase.php

core/lib/Drupal/Core/Config/StorageInterface.php

core/lib/Drupal/Core/Database/Driver/pgsql/Connection.php

core/lib/Drupal/Core/Utility/UpdateException.php

core/modules/aggregator/aggregator.test

core/modules/block/block.test

core/modules/book/book.test

core/modules/color/color.test

core/modules/comment/comment.test

core/modules/config/config.test

core/modules/contact/contact.test

core/modules/contextual/contextual.test