Catch OSError too in norm-by-med ctx manager
Catch OSError too in norm-by-med ctx manager

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