Fix actor bug arising from overwriting task specifications in the local scheduler (#513)

* copy task specifications put into the actor task cache so it won't get overwritten when the scheduler receives the next task

* cleanup

* cleanup and fix

* linting

* fix jenkins test

* fix linting

src/common/task.cc

@@ -288,6 +288,12 @@ bool TaskSpec_is_dependent_on(TaskSpec *spec, ObjectID object_id) {
   return false;
 }
 
+TaskSpec *TaskSpec_copy(TaskSpec *spec, int64_t task_spec_size) {
+  TaskSpec *copy = (TaskSpec *) malloc(task_spec_size);
+  memcpy(copy, spec, task_spec_size);
+  return copy;
+}
+
 void TaskSpec_free(TaskSpec *spec) {
   free(spec);
 }