$ git clone -n https://src.fedoraproject.org/rpms/squid.git /var/lib/mock/f40-build-799069-142138/root/chroot_tmpdir/scmroot/squid
Cloning into '/var/lib/mock/f40-build-799069-142138/root/chroot_tmpdir/scmroot/squid'...
$ git fetch origin 5580eab2d9db7b0f14a66cd8e8c17fa905490a51:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/squid
 * [new ref]         5580eab2d9db7b0f14a66cd8e8c17fa905490a51 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 5580eab new version 6.6