dependency: No point scanning for circularity on 'add'

src/dependency.cpp

@@ -67,7 +67,12 @@ void dependencyGetBlocking (const Task& task, std::vector <Task>& blocking)
 // Returns true if the supplied task adds a cycle to the dependency chain.
 bool dependencyIsCircular (const Task& task)
 {
-  std::string task_uuid = task.get ("uuid");
+
+  // A new task has no UUID assigned yet, and therefore cannot be part of any
+  // dependency chain.
+  if (task.has ("uuid"))
+  {
+    auto task_uuid = task.get ("uuid");
 
     std::stack <Task> s;
     s.push (task);
@@ -98,6 +103,7 @@ bool dependencyIsCircular (const Task& task)
 
       s.pop ();
     }
+  }
 
   return false;
 }