Woah, that is surprising. I note Bing has blogspot in its index anyway. Perhaps they use the ATOM API when they see a Blogspot URL? (technically not 'crawling')
Googled for "blogspot", picked first random domain I saw, "weliveyoung.blogspot.com", fetched "weliveyoung.blogspot.com/robots.txt" with curl, got a redirect to "weliveyoung.blogspot.co.uk/robots.txt", fetched that, voila.