You have a short story that you published, and preceding that, of course, you have the blurb to let people know the basic gist of the story. If you convert that story to film, should you keep the same blurb?
I think it's up to the creator. Personally, I'd keep the same blurb, just for continuity, unless the film was vastly different. I might add the actors names, though.
I would wait for post-production to see how it turns out. How true to the story it is, and adjust the blurb to fit the new version of the story, if needed.