Fix mapper map_task for DCR shard case.

Author: elliottslaughter

src/mapper.cc

@@ -126,7 +126,10 @@ 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
-  if (rng.uniform_range(0, 1) == 0) {
+  if (input.shard_processor.exists()) {
+    log_map.debug() << "map_task: Mapping to shard proc";
+    output.target_procs.push_back(input.shard_processor);
+  } else if (rng.uniform_range(0, 1) == 0) {
     log_map.debug() << "map_task: Mapping to all local procs";
     output.target_procs.insert(output.target_procs.end(), local_procs.begin(),
                                local_procs.end());