Support missing packages keyword in Client.get_versions (#2379)
Support missing packages keyword in Client.get_versions (#2379)

Previously users would get a non-informative error if their scheduler
was too old to support the packages= keyword.  Now we try again without
the keyword.  This is unfortunate because it drops the packages=
keyword, but is good because it will give a more informative error.
blaze/distributed,mrocklin/distributed,blaze/distributed,dask/distributed,mrocklin/distributed,mrocklin/distributed,dask/distributed,dask/distributed,dask/distributed