$ git clone -n https://src.fedoraproject.org/rpms/thunderbird.git /var/lib/mock/f40-build-746679-112826/root/chroot_tmpdir/scmroot/thunderbird
Cloning into '/var/lib/mock/f40-build-746679-112826/root/chroot_tmpdir/scmroot/thunderbird'...
$ git fetch origin c1d5e3dc1bc5d42086e3abd6e2dadf1dde5a22a8:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/thunderbird
 * [new ref]         c1d5e3dc1bc5d42086e3abd6e2dadf1dde5a22a8 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at c1d5e3d Update to 115.4.3