$ git clone -n https://src.fedoraproject.org/rpms/gnome-clocks.git /var/lib/mock/f42-build-side-1-3498235-45962/root/chroot_tmpdir/scmroot/gnome-clocks
Cloning into '/var/lib/mock/f42-build-side-1-3498235-45962/root/chroot_tmpdir/scmroot/gnome-clocks'...
$ git fetch origin 2bbcc428c3c7d1797ed910c3a2e46dd1bc127c14:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gnome-clocks
 * [new ref]         2bbcc428c3c7d1797ed910c3a2e46dd1bc127c14 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 2bbcc42 Update to 48.0