Dear ROOT developer,
reading this post reminds me that I experienced similar problems with TBB (see this post).
I have downloaded the master branch this morning and tried to compile it on an offline computer. It is still the same as what I described in my previous post (error during downloading).
I tried to disable"builtin_tbb" but it switches on automatically.
Is it planned to implement the same behaviour as the one for LZ4?
BTW, it is not mention on the Build Prerequisites page that TBB is requireds for compiling the latest ROOT version.