Yes, saw that as well. It feels that what happens is that now stemming goes before than exact quote, and therefore you get results that contains strings similar to "/event.gif". I'm saying this without knowing how Elastic search works. It's just a feeling after seeing the type of results offered.
Searching for "/event.gif?" (including the quotes) provides better results, apparently. The slash and the question mark are kind of ignored, but the results offered do contain all "event.gif"