Issue #2926309 by vaplas, alexpott, mpdonadio, tacituseu, Mixologic: Random fail due to APCu not being able to allocate memory

Issue #2776975 by joelpittet, dawehner, tim.plunkett, xjm, pfrenssen: March 3, 2017: Convert core to array syntax coding standards for Drupal 8.3.x RC phase

Issue #2210521 by mitrpaka, vlad.n, Ema.jar, donquixote, dawehner, klausi, alexpott: Settings::getInstance() should throw an exception if called before being initialized

Issue #2665992 by alexpott, klausi, heykarthikwithu, xjm, tstoeckler: @file is not required for classes, interfaces and traits

Issue #2575495 by webflo, Mile23, hussainweb: Invalidate APCu Class Loader automatically if necessary

Issue #2384675 by sidharrell, cilefen, Mile23, damiankloip, dawehner, Wim Leers, alexpott, neclimdul: Deprecate conf_path()

Issue #2474909 by alexpott, mpdonadio, znerol, catch, Wim Leers, Berdir: Allow Simpletest to use the same APC user cache prefix so that tests can share the classmap and other cache objects

Issue #2463321 by amateescu: Serializing the database connection is dangerous and error-prone, make it unserializable again

Issue #2347877 by znerol, Berdir: Move DrupalKernel::initializeCookieGlobals() into a SessionConfiguration service

Issue #2199795 by andypost, twistor, martin107, larowlan, andyceo: Make the Settings class prevent serialization of actual settings

Issue #2328111 by dawehner, martin107, neclimdul: Replace most instances of the DRUPAL_ROOT constant with the app.root container parameter.

Issue #2288665 by znerol: Remove _maintenance request attribute and replace it with a maintenance mode service.

Issue #2016629 by larowlan, neclimdul, sun, alexpott, jibran, ParisLiakos, donquixote, effulgentsia, msonnabaum: Refactor bootstrap to better utilize the kernel.

Revert "Issue #2016629 by larowlan, neclimdul, sun, alexpott, jibran, ParisLiakos, donquixote, effulgentsia, msonnabaum: Refactor bootstrap to better utilize the kernel."

This reverts commit cda051c4.

Issue #2016629 by larowlan, neclimdul, sun, alexpott, jibran, ParisLiakos, donquixote, effulgentsia, msonnabaum: Refactor bootstrap to better utilize the kernel.