$ git clone -n https://src.fedoraproject.org/rpms/menu-cache.git /var/lib/mock/f39-build-1465629-33600/root/chroot_tmpdir/scmroot/menu-cache
Cloning into '/var/lib/mock/f39-build-1465629-33600/root/chroot_tmpdir/scmroot/menu-cache'...
$ git fetch origin 326133b8946c6225b3ffb194d0682f3cecd99e78:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/menu-cache
 * [new ref]         326133b8946c6225b3ffb194d0682f3cecd99e78 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 326133b Update to the latest git