$ git clone -n https://src.fedoraproject.org/rpms/boost.git /var/lib/mock/f40-build-777660-129469/root/chroot_tmpdir/scmroot/boost
Cloning into '/var/lib/mock/f40-build-777660-129469/root/chroot_tmpdir/scmroot/boost'...
$ git fetch origin 932a39a6871cab3dbd09aaaeba02949cbcf7290c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/boost
 * [new ref]         932a39a6871cab3dbd09aaaeba02949cbcf7290c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 932a39a Rebuild for ICU 74