is_user_member_of_blog() [no args] should return true for logged in users on...

is_user_member_of_blog() [no args] should return true for logged in users on single site. $wpdb->blogid is 0, but the current blog ID isn't. Fixes #19160.


git-svn-id: https://core.svn.wordpress.org/trunk@19209 1a063a9b-81f0-0310-95a4-ce76da25c4cd