$ git clone -n https://src.fedoraproject.org/rpms/moarvm.git /var/lib/mock/f40-build-2265381-54598/root/chroot_tmpdir/scmroot/moarvm
Cloning into '/var/lib/mock/f40-build-2265381-54598/root/chroot_tmpdir/scmroot/moarvm'...
$ git fetch origin efffb5edbd00c2aaa15ffd34d591d25474b3a364:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/moarvm
 * [new ref]         efffb5edbd00c2aaa15ffd34d591d25474b3a364 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at efffb5e remove source file