Manual:$wgSecureLogin/ja

詳細
If true, forces users to authenticate using https when they come from http, but only if you use a protocol-relative URL in  (otherwise this setting is ignored).

From 1.22 on, use  to set   false by default if you want HTTP users to stay on HTTP after login by default.

wikitech-l での George Herbert のアイデアに基づいています: wikitech-l/2010-October/050071.html

$wgServer に以下のように設定する必要があります.