Background Updates: Fix a PHP fatal error which could be encountered on some systems when using FTP.

Merges [26148] from 3.8 to the 3.7 branch.

props dd32.
fixes #25817.

Built from https://develop.svn.wordpress.org/branches/3.7@27881


git-svn-id: http://core.svn.wordpress.org/branches/3.7@27712 1a063a9b-81f0-0310-95a4-ce76da25c4cd
When checking filesystem permissions for core updates, only check the permissions of the files which we need to alter.

Merges [26014] from 3.8 to the 3.7 branch.

fixes #25771.

Built from https://develop.svn.wordpress.org/branches/3.7@27882


git-svn-id: http://core.svn.wordpress.org/branches/3.7@27713 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Core Upgrader success statistics: Pass the version of WordPress we're upgrading from, as well as the version being upgraded to.

Merges [26016] and [26017] from 3.8 to the 3.7 branch.

fixes #25772.

Built from https://develop.svn.wordpress.org/branches/3.7@27883


git-svn-id: http://core.svn.wordpress.org/branches/3.7@27714 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Updates: When a failed Background Update occurs, only show the failed update nag if the user hasn't yet updated if it was an early abort.

Merges [26186] from 3.8 to the 3.7 branch.

props SergeyBiryukov.
fixes #25887.

Built from https://develop.svn.wordpress.org/branches/3.7@27884


git-svn-id: http://core.svn.wordpress.org/branches/3.7@27715 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Core Updates: Fix a case where options (db_version specifically) can end up with stale values in the cache after a update is performed.

Merges [26448] and [26734] from 3.8 to the 3.7 branch.

props dd32.
fixes #26173.

Built from https://develop.svn.wordpress.org/branches/3.7@27885


git-svn-id: http://core.svn.wordpress.org/branches/3.7@27716 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Cron: Fix a case where a cache inconsistency can cause wp_clear_scheduled_hook() to enter an infinite loop.

Merges [26782] from 3.8 to the 3.7 branch.

props dd32.
fixes #25773.

Built from https://develop.svn.wordpress.org/branches/3.7@27886


git-svn-id: http://core.svn.wordpress.org/branches/3.7@27717 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Fix a regression in wp_mkdir_p() where the $mode of the parent folder is not correctly applied to all created paths.

Merges [26449] and [26927] from 3.8.x to the 3.7 branch.

props dd32.
fixes #25822.

Built from https://develop.svn.wordpress.org/branches/3.7@27887


git-svn-id: http://core.svn.wordpress.org/branches/3.7@27718 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Prefix the notoptions cache key in the multisite site-options group with $wpdb->siteid to avoid collisions.

Merges [26304] (and [26305]) from 3.8 to the 3.7 branch.

props wonderboymusic.
fixes #25883.

Built from https://develop.svn.wordpress.org/branches/3.7@27888


git-svn-id: http://core.svn.wordpress.org/branches/3.7@27719 1a063a9b-81f0-0310-95a4-ce76da25c4cd