Currently the update test script will only output warning if all functions have conflict under different run lines with same prefix, and be silent if part of them conflict. This looks counterintuitive and leads to confusion sometimes.
I think the warn only conflicting for all functions is used for the multi prefixes case, e.g. --check-prefixes=A,B;--check-prefixes=A,C when we hope the conflicted functions use B and C respectively. Under which case, warn A conflicted is annoying.