[TTree] Deleted friend trees are not deregistered from their friend

#include <TTree.h>

#include <iostream>

int main()

{

   auto tree = new TTree("t", "t");

   auto friendTree = new TTree("s", "s");

   tree->AddFriend(friendTree);

   TTree cloneTree("q", "q");

   tree->AddClone(&cloneTree);

   int x;

   cloneTree.Branch("x", &x);

   delete friendTree;

   // prints 1 although the friend is already deleted

   std::cout << tree->GetListOfFriends()->GetEntries() << std::endl;

   // crashes trying to access the contents of the friend TTree

   delete tree;

   return 0;

}