Source: r-cran-sf Version: 0.9-6+dfsg-1 Severity: serious Tags: ftbfs r-cran-sf build depends on r-cran-s2 that is only available on amd64/ppc64/ppc64el/x32 (see #976473).
Since the new r-cran-sf build dependency seems to be only required for tests, removing it (also from the autopkgtest?) might be the easiest short-term solution.