Fix positivity-weights missmatch
Created by: scarlehoff
This might fix the problems mentioned in #976 (closed), here's a quick example (I'm still running a full fit @wilsonmr, I should have ~50 replicas of the 70k fit by tomorrow). The problem seems to be solved (orange is before the fix).
WIP since the missing reload
at the end of the fit could have an effect on the final fit (on the % of replicas that exhaust the training length)