$ git clone -n https://src.fedoraproject.org/rpms/R-pkgdown.git /var/lib/mock/f40-build-1944534-25177/root/chroot_tmpdir/scmroot/R-pkgdown
Cloning into '/var/lib/mock/f40-build-1944534-25177/root/chroot_tmpdir/scmroot/R-pkgdown'...
$ git fetch origin bb95d17f0a35f2b6ed5beed7ae4496da145d96f2:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-pkgdown
 * [new ref]         bb95d17f0a35f2b6ed5beed7ae4496da145d96f2 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at bb95d17 R-maint-sig mass rebuild