Theme Upgrader: Be super-careful and check the contents of the $wp_theme_directories variable before merging it, if someone has changed it directly, or worse, unset it, this could've resulted in the $protected_directories being empty. See [25082] See #22501

Built from https://develop.svn.wordpress.org/trunk@25180


git-svn-id: http://core.svn.wordpress.org/trunk@25152 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Plugin Upgrader: Plugin_Upgrader::upgrade() returns nothing in event of success, every other install(), upgrade() and bulk_upgrade() method returns true, so return true; 

Built from https://develop.svn.wordpress.org/trunk@25181


git-svn-id: http://core.svn.wordpress.org/trunk@25153 1a063a9b-81f0-0310-95a4-ce76da25c4cd