avoid filling the filtered partition maps with 0s
avoid filling the filtered partition maps with 0s

jas14/khmer,ged-lab/khmer,F1000Research/khmer,Winterflower/khmer,kdmurray91/khmer,souravsingh/khmer,ged-lab/khmer,F1000Research/khmer,jas14/khmer,Winterflower/khmer,kdmurray91/khmer,souravsingh/khmer,kdmurray91/khmer,Winterflower/khmer,F1000Research/khmer,ged-lab/khmer,jas14/khmer,souravsingh/khmer