* Show a notice for beta testers on update-core.php explaining the status of their install. Three possibilities: auto updates are enabled, auto updates are disabled because the install doesn't support SSL HTTP requests, and auto updates are disabled because it is a VCS checkout.
* Improve the output of the email, for maximum debugging potential. Failures are clearly labeled and the email leads testers to the support forums and Trac.
* Try to create wp-content/languages in the upgrader if it doesn't exist. Our mkdir isn't recursive, so trying to create wp-content/languages/plugins could fail.
* Abstract out version control checkout determination into a public method. The filter is now auto_upgrade_is_vcs_checkout, still subject to change.
see #22704.
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git-svn-id: http://core.svn.wordpress.org/trunk@25550 1a063a9b-81f0-0310-95a4-ce76da25c4cd