Core: do not recalculate state weight after commands without data. If @sum is 0 it could not be increased via multiplying by 10 - skip this and use first state.

Write-commit without data is good case but it resets state weight to 0. After that dnet_weight_get_winner gets sum=0 that leads to endless loop. Commands without data (null data) mustn't change the weight of a state.
Endless loop is bad too that's why we have to ends it and use first available state.
Isn't it the same?
sum < 0 will not execute loop body when sum == 0