This was built against LLVM 5.0, which is not in stable yet, so this update should be held back until LLVM 5.0 goes stable.
Thanks, I've been trying to figure out what is going on here and it sounds like it might be some kind of bug with the composes. I may try push this to updates to see if it that repository has the same issue.
The arm tests aren't hanging on f25, so they don't need to be disabled here.
The LLVM5 update has just been created: https://bodhi.fedoraproject.org/updates/FEDORA-2018-8014b75c0d