Issue #2387443 by alexpott, dawehner: BinaryFileResponse can fail because the core MIME guessing is not added to the MimeType singleton
Issue #2380607 by Berdir, dawehner: Do not call ConfigBase::validateKeys() for data loaded from storage
Issue #2388043 by daffie: Remove DrupalUnitTestBase
Issue #2084987 by andypost, Jalandhar: Remove usage of field_ui_default_value and recommend proper replacement
Issue #2263359 by jhodgdon: hook_help(): Top of page help sections can't link to help pages without a fatal error or checking for help module