set_current_screen() is now unnecessary in Automatic_Upgrader_Skin, which is good because it breaks things in the network admin.

fixes #25622.

Built from https://develop.svn.wordpress.org/trunk@25836


git-svn-id: http://core.svn.wordpress.org/trunk@25748 1a063a9b-81f0-0310-95a4-ce76da25c4cd