Try to make py2.7 tests not always pass.
Try to make py2.7 tests not always pass.

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