Currently r-minimal depends on texlive-latex-xkeyval, which depends on texlive-ms, which for a reason I do not see pulls in the valgrind variable.
This is at version 3.17, which fails on powerpc64le. The user facing variable valgrind/interactive, however, is at 3.20, and it builds. After the impending core-updates merge, we should update valgrind to 3.20. I am opening a bug so that this is not forgotten. Andreas