[hist] Prevent "Replacing existing TH1" in THn test.
[hist] Prevent "Replacing existing TH1" in THn test.

root-mirror/root,olifre/root,root-mirror/root,karies/root,olifre/root,root-mirror/root,root-mirror/root,karies/root,karies/root,karies/root,olifre/root,root-mirror/root,root-mirror/root,olifre/root,karies/root,karies/root,karies/root,root-mirror/root,olifre/root,olifre/root,karies/root,olifre/root,olifre/root,karies/root,root-mirror/root,root-mirror/root,karies/root,root-mirror/root,olifre/root,karies/root,olifre/root,olifre/root,root-mirror/root