Example failure:

 562/1224 Test  #541: tutorial-gl-gltf3 ...................................................***Failed  Error regular expression found in output. Regex=[Error in <]  1.36 sec
Processing /builddir/build/BUILD/root-6.26.00/tutorials/gl/gltf3.C...
Error in <TList::Delete>: A list is accessing an object (0x7fffd1c959a0) already deleted (list name = Functions)
Error in <TList::Delete>: A list is accessing an object (0x7fffd1c95750) already deleted (list name = Functions)