$ git clone -n https://src.fedoraproject.org/rpms/gmp.git /var/lib/mock/f42-build-side-1-3498198-45961/root/chroot_tmpdir/scmroot/gmp
Cloning into '/var/lib/mock/f42-build-side-1-3498198-45961/root/chroot_tmpdir/scmroot/gmp'...
$ git fetch origin deaec306787afa77a2c28f5829fa0be1d9269ab1:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gmp
 * [new ref]         deaec306787afa77a2c28f5829fa0be1d9269ab1 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at deaec30 Fix build with GCC 15 (rhbz#2340240)