Add small optimization to median_at_least reducing the number of branches
Add small optimization to median_at_least reducing the number of branches

souravsingh/khmer,Winterflower/khmer,F1000Research/khmer,jas14/khmer,F1000Research/khmer,Winterflower/khmer,jas14/khmer,ged-lab/khmer,F1000Research/khmer,souravsingh/khmer,jas14/khmer,Winterflower/khmer,ged-lab/khmer,ged-lab/khmer,souravsingh/khmer