$ git clone -n https://src.fedoraproject.org/rpms/thunderbird.git /var/lib/mock/f41-build-side-1-2907919-34729/root/chroot_tmpdir/scmroot/thunderbird
Cloning into '/var/lib/mock/f41-build-side-1-2907919-34729/root/chroot_tmpdir/scmroot/thunderbird'...
$ git fetch origin bb39515b12560f79e7cad8d305131c5acdac5a09:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/thunderbird
 * [new ref]         bb39515b12560f79e7cad8d305131c5acdac5a09 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at bb39515 Update to 128.3.0