$ git clone -n https://src.fedoraproject.org/forks/catme0w/rpms/R-waldo /var/lib/mock/f41-build-side-1-3148568-40058/root/chroot_tmpdir/scmroot/R-waldo
Cloning into '/var/lib/mock/f41-build-side-1-3148568-40058/root/chroot_tmpdir/scmroot/R-waldo'...
$ git fetch origin 5cbd2c057823ac1a61e873f6bf0746c66d1693d7:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/forks/catme0w/rpms/R-waldo
 * [new ref]         5cbd2c057823ac1a61e873f6bf0746c66d1693d7 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 5cbd2c0 Update R-waldo.spec