$ git clone -n https://src.fedoraproject.org/rpms/libcaca.git /var/lib/mock/f40-build-801357-143771/root/chroot_tmpdir/scmroot/libcaca
Cloning into '/var/lib/mock/f40-build-801357-143771/root/chroot_tmpdir/scmroot/libcaca'...
$ git fetch origin 9c9187befd5ca8de14e7a465072b15be10c3df15:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/libcaca
 * [new ref]         9c9187befd5ca8de14e7a465072b15be10c3df15 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 9c9187b Disable ruby bindings on F40+ (workaround RHBZ#2261303)