Fix mapper map_task for DCR shard (part 2).

Author: elliottslaughter

src/mapper.cc

@@ -126,6 +126,7 @@ void FuzzMapper::map_task(const MapperContext ctx, const Task &task,
   log_map.debug() << "map_task: Selected variant " << output.chosen_variant;
 
   // TODO: assign to variant's correct processor kind
+  output.target_procs.clear();
   if (input.shard_processor.exists()) {
     log_map.debug() << "map_task: Mapping to shard proc";
     output.target_procs.push_back(input.shard_processor);