Errors in Map and Reduce now get printed where they happen.
Errors in Map and Reduce now get printed where they happen.

This avoids the constantly annoying situation where we'll get an error
and not know where it came from.

klucar/pachyderm,sambooo/pachyderm,ShengjieLuo/pachyderm,sambooo/pachyderm,alexdebrie/pachyderm,pachyderm/pfs,phacops/pachyderm,wideioltd/pachyderm,alexdebrie/pachyderm,sambooo/pachyderm,klucar/pachyderm,ShengjieLuo/pachyderm,ShengjieLuo/pachyderm,klucar/pachyderm,kunthar/pachyderm,kunthar/pachyderm,henrylee2cn/pachyderm,alexdebrie/pachyderm,phacops/pachyderm,wideioltd/pachyderm,pachyderm/pfs,henrylee2cn/pachyderm,pachyderm/pfs