Test that from_filenames uses full path.
Test that from_filenames uses full path.

freeman-lab/dask,blaze/dask,mraspaud/dask,wiso/dask,jcrist/dask,dask/dask,jakirkham/dask,dask/dask,hainm/dask,jayhetee/dask,esc/dask,wiso/dask,cowlicks/dask,marianotepper/dask,ssanderson/dask,clarkfitzg/dask,chrisbarber/dask,vikhyat/dask,PhE/dask,gameduell/dask,mrocklin/dask,ContinuumIO/dask,mikegraham/dask,simudream/dask,marianotepper/dask,blaze/dask,jayhetee/dask,vikhyat/dask,simudream/dask,freeman-lab/dask,ssanderson/dask,ContinuumIO/dask,mrocklin/dask,cpcloud/dask,pombredanne/dask,mraspaud/dask,esc/dask,clarkfitzg/dask,jcrist/dask,pombredanne/dask,hainm/dask,jakirkham/dask,PhE/dask