fix from_s3 test
fix from_s3 test

dask/dask,dask/dask,ContinuumIO/dask,blaze/dask,gameduell/dask,jcrist/dask,cpcloud/dask,mraspaud/dask,mrocklin/dask,chrisbarber/dask,mraspaud/dask,jakirkham/dask,blaze/dask,mikegraham/dask,cowlicks/dask,jcrist/dask,jakirkham/dask,ContinuumIO/dask,mrocklin/dask