to_parquet trims protocol from paths (#3080)
to_parquet trims protocol from paths (#3080)

Previously this wasn't handled, and wasn't caught because `s3fs` strips
protocols internally automatically.
jakirkham/dask,blaze/dask,jcrist/dask,mrocklin/dask,ContinuumIO/dask,dask/dask,mrocklin/dask,dask/dask,ContinuumIO/dask,jcrist/dask,jakirkham/dask,blaze/dask