$ git clone -n https://src.fedoraproject.org/rpms/R-Rcpp.git /var/lib/mock/f39-build-1536737-36340/root/chroot_tmpdir/scmroot/R-Rcpp
Cloning into '/var/lib/mock/f39-build-1536737-36340/root/chroot_tmpdir/scmroot/R-Rcpp'...
$ git fetch origin d16a832b7f39b5e85f6bfbb316c8f65dc01b1795:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-Rcpp
 * [new ref]         d16a832b7f39b5e85f6bfbb316c8f65dc01b1795 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at d16a832 Fix build requires