$ git clone -n https://src.fedoraproject.org/rpms/R-BiocFileCache.git /var/lib/mock/f40-build-1930417-25111/root/chroot_tmpdir/scmroot/R-BiocFileCache
Cloning into '/var/lib/mock/f40-build-1930417-25111/root/chroot_tmpdir/scmroot/R-BiocFileCache'...
$ git fetch origin 11f04c3987ba4b773196249948d61ac609523584:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-BiocFileCache
 * [new ref]         11f04c3987ba4b773196249948d61ac609523584 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 11f04c3 R-maint-sig mass rebuild