Fix for CONNECTORS-993.  Pipeline code now has an explicit path for handling the no-document case.

git-svn-id: https://svn.apache.org/repos/asf/manifoldcf/trunk@1610987 13f79535-47bb-0310-9956-ffa450edef68
Fix for CONNECTORS-995.

git-svn-id: https://svn.apache.org/repos/asf/manifoldcf/trunk@1610996 13f79535-47bb-0310-9956-ffa450edef68