$ git clone -n https://src.fedoraproject.org/rpms/aerc.git /var/lib/mock/f39-build-1899998-42833/root/chroot_tmpdir/scmroot/aerc
Cloning into '/var/lib/mock/f39-build-1899998-42833/root/chroot_tmpdir/scmroot/aerc'...
$ git fetch origin d12a4b4c2f3b2df24d2c8c64c61b0e57fa2ac42e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/aerc
 * [new ref]         d12a4b4c2f3b2df24d2c8c64c61b0e57fa2ac42e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at d12a4b4 Rebuilt for https://fedoraproject.org/wiki/Fedora_39_Mass_Rebuild