Merge branch '8.x' of git.drupal.org:project/drupal into 8.x

core/includes/common.inc

core/includes/update.inc

core/modules/book/book.module

core/modules/book/book.pages.inc

core/modules/config/config.test

core/modules/file/file.field.inc

...es/simpletest/tests/config_upgrade/config/config.test.xml

...dules/simpletest/tests/config_upgrade/config_upgrade.info

...les/simpletest/tests/config_upgrade/config_upgrade.module