Issue #987930 by David_Rothstein, Tor Arne Thune: Fixed The obsolete 'site_offline_message' variable is not always deleted during the D6->D7 upgrade.

Issue #1226796 by sun, catch, Damien Tournoud: Fixed Not equal operator '!=' is not supported by all databases, must be '<>'.

Issue #1164852 follow-up by plach, chx, Boobaa, sun: Fixed critical regression: Node bodies display as empty after upgrade to 7.7 from 6.x if the nodes have a language.

Issue #1231856 by lyricnz: Fixed menu_update_7001() breaks when updating from 7.4 or upgrading from D6.

#1006478 by Stevel, mradcliffe, vwX, bfroehle: Fixed D6 to D7 upgrade on PostgreSQL stopped cold at update.php

#945112 by carlos8f, dalin, David_Rothstein: Fixed Unable to stay logged in during upgrade from D6 -> D7

#984358 by dalin, David_Rothstein: Fixed Upgrade from 6.x to 7.x always pulls your site out of maintenance mode immediately

- Patch #912700 by bleen18, jmiccolis: modules with no files[] entries in .info files are deemed 'incompatible with 7.x'.

#887288 by catch, David_Rothstein: Fixed Attempting to use update.php without having configured a database in settings.php results in incorrect/misleading error message

- Patch #818374 by Damien Tournoud, ksenzee, Dave Reid: add a requirements check error if PECL PDO is being used.

#864464 follow-up by David_Rothstein: Move notice about requiring latest version of Drupal so it only comes up the first time update.php is ran.

#864464 by heyrocker, Beanjammin: Ensure people using Drupal < 6.16 that they must upgrade to latest version, rather than showing them a WSOD.

- Patch #909272 by moshe weitzman, David_Rothstein: remove stub update functions and renumber the remaining ones.

- Patch #894530 by David_Rothstein: update system calls drupal_get_schema_versions() for lots of uninstalled modules, leading to a performance hit.

- Patch #790482 by glipay: update_prepare_d7_bootstrap() docs say it should not modify database, but it does.