When a banner is previewed in a language other than English, {{int:...}} messages don't get translated. This bug doesn't occur in the live CentralNotice on meta, but does occur locally. Banners served from the BannerLoader also do not have this problem.
Apparently {{int:...}} translation is broken if wfMsg() is called at any point before the translation with a messagekey set to a message that includes anything in double braces. In this case, the int messages just display in English rather than the requested language.
Since every SpecialPage is supposed to call setHeaders(), and since setHeaders() sets the page title using the 'pagetitle' message, which is defined as '$1 - {{SITENAME}}', the only way to avoid this is to move the setHeader() calls to the end of the code, which is rather messy.
Version: unspecified
Severity: trivial