In org.webharvest.runtime.processors.HttpProcessor.execute(Scraper scraper, ScraperContext context) the response is tried to convert to a string, if MIME-Type starts with "text" or "application/xml" or if it is null. For me I added also "application/rss". If the charset is not used, the encoding gets broken, because it is not considered (body.toString in BaseProcessor).
bugfixed HttpProcessor