I’ve mostly been following the Scandinavian tabloid papers, and it seems they couldn’t really decide which narrative to go with; before or during Berlin. At least according to the more reputable Scandinavian news outlets, the rumor started out with a rumor about a t-positive ‘during’ Berlin, and then transformed into a ‘before’ Berlin rumor.
The way I read the official statement by IAAF is that they’re now debunking both possibilities, thus “… all the athletes involved in this final have also tested negative in all other tests carried out prior to the 100m final …” (emphasis mine).