$ git clone -n https://src.fedoraproject.org/rpms/thunderbird.git /var/lib/mock/f41-build-59218432-6571984/root/chroot_tmpdir/scmroot/thunderbird
Cloning into '/var/lib/mock/f41-build-59218432-6571984/root/chroot_tmpdir/scmroot/thunderbird'...
$ git fetch origin c6c60c7e9ae7bc2a9a7606c5a5e98d2b879be6ac:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/thunderbird
 * [new ref]         c6c60c7e9ae7bc2a9a7606c5a5e98d2b879be6ac -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at c6c60c7 Update to 128.10.0