Use getInTree in insert

ConflictSet.cpp

@@ -1732,9 +1732,7 @@ void addWriteRange(Node *&root, int64_t oldestVersion,
     n = child;
   }
 
-  Node **useAsRoot = n->parent == nullptr
-                         ? &root
-                         : &getChildExists(n->parent, n->parentsIndex);
+  Node **useAsRoot = &getInTree(n, impl);
 
   int consumed = lcp - remaining.size();