Does it work on Chrome (nightly or with that support enabled)?
Does anybody disagree that this is a no brainer for Mozilla: they should work that around ASAP (with a HTTP/2 blacklist for example). The impact is so high and it affects too many users.
Also note that Google in its deepest feelings wants FF down so this may by even intentional since people will always blame the client.
Also, this hash function is linear so it has the equivalent substrings property.
One can take advantage of it and be able to generate preimages even faster. Take a preimage and find m equivalent strings for n substrings of it. Replacing the substring with their equivalent will get you n to the m-th preimages that hash to the same value.