Previous announcement: https://lists.wikimedia.org/pipermail/mediawiki-api-announce/2014-September/...
During the 1.25 development cycle, the API has been warning you if you're specifying neither the "continue" nor "rawcontinue" parameters to action=query. Recently this warning was targeted more specifically to queries that actually return continuation data. The time is coming soon for making this change, so please check your bots, bot frameworks, scripts, and so on to ensure that you won't be broken when this change is made.
If you want to continue using your existing continuation code unchanged, all you need to do is add the "rawcontinue" parameter to your action=query queries.
If you'd rather change to the easier-to-get-right new style, add an empty "continue" parameter to your initial action=query queries. See https://www.mediawiki.org/wiki/API:Query#Continuing_queries for details on the new mechanism.
If you do nothing, sometime in the next few months your code will likely start thinking that no queries ever need continuation when the default is changed to return the new 'continue' node rather than the old 'query-continue'. I'll send an announcement when the specific date is decided, but I don't promise more than a week's notice.