Issue #2454649 by Aki Tendo, dawehner: Cache Optimization and hardening -- [PP-1] Use assert() instead of exceptions in Cache::merge(Tags|Contexts)

Issue #2578989 by ifrik, alvar0hurtad0, jhodgdon, Bojhan, snehi, mairi, rachel_norfolk: Update link descriptions on the Configuration page that are not correct for D8

Issue #2410497 by alvar0hurtad0, sdstyles, hussainweb, webchick, jhodgdon, mpdonadio: Update remaining url() and _l() calls in comments/documentation

Issue #2576533 by alexpott, stefan.r, Wim Leers, dawehner, xjm, effulgentsia, catch: Rename SafeStringInterface to MarkupInterface and move related classes

Issue #2380389 by webflo, Mile23, davidwbarratt, timmillwood, hussainweb, tstoeckler, bojanz, yched, MKorostoff, alexpott, webchick: Use a single vendor directory in the root

Issue #2554267 by asgorobets, justAChris, LoMo: Clean Environment button on Simpletest UI should not run test even if tests are selected

Issue #2493475 by ifrik, walangitan, XaviP, jhodgdon, batigolix: Fix online docs references in Help to conform to our standards

Issue #2551453 by LoMo, Ayesh, jaxxed, LinL, madhavvyas, Miraya: Follow-up: Consistently use "email" instead of "e-mail" in Drupal

Issue #2571291 by pwolanin, aneek, stefan.r: In WebTest code, assertEqual and assertIdentical should always show the 2 values on failure

Issue #2570355 by Sutharsan, stefan.r, kgoel, josephdpurcell, joelpittet, justAChris, dawehner, pfrenssen, pwolanin, David_Rothstein, catch: Replace remaining !placeholder and @placeholder with :placeholder for URLs

Issue #2571375 by alexpott, webflo, stefan.r, Xano, mr.baileys: Remove TranslationManager dependency from LanguageManager

Issue #2560783 by stefan.r, joelpittet, lauriii, Cottser, Sutharsan, kgoel, justAChris, Gábor Hojtsy, dawehner, jhodgdon, effulgentsia, xjm, andypost, googletorp: Replace !placeholder with :placeholder for URLs in hook_help() implementations

Issue #2557113 by stefan.r, alexpott, dawehner, joelpittet, cilefen, lauriii, plach, catch, chx, xjm: Make t() return a TranslationWrapper object to remove reliance on a static, unpredictable safe list

Issue #2477223 by Mile23, Wim Leers, j2r, ianthomas_uk, jaimeguzman, pjbaert: Refactor _drupal_add_html_head, drupal_get_html_head, _drupal_add_html_head_link into the attachments processor, remove from common.inc

Issue #2545972 by alexpott, joelpittet, ericjenkins, stefan.r, Wim Leers, Cottser: Remove all code usages SafeMarkup::checkPlain() and rely more on Twig autoescaping

Issue #2566447 by stefan.r, joelpittet, alexpott, lauriii, dawehner: Cast safe string objects to string or use assertEqual() in some assertIdentical() comparisons

Issue #2560643 by chx, Mixologic, dawehner, larowlan: Fatal PHPUnit tests are not always reported as failure

Issue #2560729 by stefan.r, lauriii: Cast objects implementing SafeStringInterface to string in TestBase / WebTestBase

Issue #2565671 by joyceg, Aki Tendo: Misspelling in core/modules/simpletest/src/Tests/SimpleTestTest.php

Issue #2564353 by alexpott, joelpittet, xjm, justAChris, nlisgo, subhojit777: Remove !placeholder usage from SafeMarkup::format()

Issue #2558191 by sdstyles: Remove usage of deprecated UrlGeneratorInterface::generateFromPath() in  WebTestBase::drupalHead()

Issue #2487592 by alexpott, JeroenT, Schnitzel, cilefen: CMI: don't ship with a default "active" directory that is empty in most Drupal installations

Issue #1031122 by alexpott, greg.1.anderson, catch, sun, stefan.r, pwolanin: postgres changeField() is unable to convert to bytea column type correctly

Issue #2555169 by TR: API documentation should not suggest using deprecated function format_string()

Issue #2560641 by alexpott, lauriii, Xano, borisson_, ianthomas_uk, olli: Remove all usages SafeMarkup::checkPlain() from render arrays

Revert "Issue #2560641 by alexpott, lauriii, Xano, borisson_, ianthomas_uk: Remove all usages SafeMarkup::checkPlain() from render arrays"

This reverts commit 31007609.

Issue #2560641 by alexpott, lauriii, Xano, borisson_, ianthomas_uk: Remove all usages SafeMarkup::checkPlain() from render arrays

Issue #507488 by lauriii, mdrummond, Wim Leers, Manuel Garcia, pwolanin, davidhernandez, chx, jibran, andypost, dawehner, Xano, tuutti, Gábor Hojtsy, LewisNyman, maximiliam, eiriksm, borisson_, bill richardson, Fabianx, joelpittet, Jeff Burnz, xjm, webchick, Bojhan, EclipseGc, emma.maria, tim.plunkett: Convert page elements (local tasks, actions) into blocks

Issue #2559605 by Cottser, stefan.r: Convert SafeMarkup::checkPlain() in render arrays to #plain_text