Fix a segfault.
Fix a segfault.

alexdebrie/pachyderm,sambooo/pachyderm,ShengjieLuo/pachyderm,klucar/pachyderm,sambooo/pachyderm,ShengjieLuo/pachyderm,alexdebrie/pachyderm,klucar/pachyderm,sambooo/pachyderm,ShengjieLuo/pachyderm,alexdebrie/pachyderm,klucar/pachyderm