$ git clone -n https://src.fedoraproject.org/rpms/firefox.git /var/lib/mock/f41-build-861219-169528/root/chroot_tmpdir/scmroot/firefox
Cloning into '/var/lib/mock/f41-build-861219-169528/root/chroot_tmpdir/scmroot/firefox'...
$ git fetch origin 2223db9e0fdf33a3742697805b3e5a25b99462d1:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/firefox
 * [new ref]         2223db9e0fdf33a3742697805b3e5a25b99462d1 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 2223db9 Updated to 132.0.1