Issue #1798732 by Dean Reilly, westie, alexpott, sun: convert install_task() variable to use state system.

Issue #1149866 by jessebeach, effulgentsia, ethanw, corbacho, et al: Added Backbone.js and Underscore.js to core.

Issue #1723892 by Berdir, Pancho, das-peter, fago: Support for revisions for entity save and delete operations.

Issue #843114 by sun, quicksketch, Berdir, c960657, Crell: Fixed DatabaseConnection::__construct() and DatabaseConnection_mysql()::__construct() leaks  (Too many connections).

Issue #1810652 by xjm: Fixed admin/config/system/site-information still references the default content feed when node.module is disabled.

Issue #1798732 by Dean Reilly, westie, alexpott: Convert install_task() variable to use state system.

Issue #1802072 by fubhy, Stalski: Ajax callbacks should be callbacks defined as function or class method.

Issue #1808112 by sun: Fixed Missing method visibility, bogus phpDoc and coding style in Cache backend classes.

Issue #1431658 by Albert Volkman, xjm, kid_icarus, ChinggizKhan, rgristroph, connork: Massive API docs cleanup for system tests

Issue #1778942 by yched, tstoeckler, andypost: Fixed Discovery::getDefinition() / getDefinitions() : inconsistent return values for 'no result.
git commit -am Issue

Issue #1717678 by andypost, Berdir, attiks: Fixed Entity::createDuplicate() does not account for uuid property.

Issue #1788462 by samhassell: Remove references to 'active store' in comments for configuration system.

Issue #1608842 by chx, alexpott, sun, effulgentsia, beejeebus, tim.plunkett et al: Replace list of bootstrap modules, enabled modules, enabled themes, and default theme with config.

Issue #1480854 by tim.plunkett, Noyz, Bojhan, yoroy, kika: Convert operation links to '#type' => 'operations'.

Issue #1642526 by andypost, Berdir, dixon_: Add upgrade path from for generating UUIDs for all core entities.

Issue #1805776 by psynaptic, Eric_A, rbayliss: Fixed Fatal error: Class 'Drupal\Core\Template\ArrayIterator' not found in core/lib/Drupal/Core/Template/Attribute.php.

Issue #1642062 by tim.plunkett, xjm, chx, merlinofchaos, damiankloip, dawehner, Berdir, aspilicious, Fabianx: Add TempStore for persistent, limited-term storage of non-cache data.

Issue #742344 by sun, pillarsdotnet, tarmstrong, neilnz, wamilton, lucascaro: Allow forms to set custom validation error messages on required fields.

Issue #1742438 by larowlan, Christian Biggins, kim.pepper, Everett Zufelt: Fixed Vertical tabs header and container rendered even when no vertical tabs.