$ git clone -n https://src.fedoraproject.org/rpms/firefox.git /var/lib/mock/f42-build-side-1-3580337-46819/root/chroot_tmpdir/scmroot/firefox
Cloning into '/var/lib/mock/f42-build-side-1-3580337-46819/root/chroot_tmpdir/scmroot/firefox'...
$ git fetch origin f9741e8a6c128cb4671737786c59c67e1293c05d:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/firefox
 * [new ref]         f9741e8a6c128cb4671737786c59c67e1293c05d -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f9741e8 Merge branch 'main' into f42