$ git clone -n https://src.fedoraproject.org/rpms/tlpi.git /var/lib/mock/f40-build-2488197-61651/root/chroot_tmpdir/scmroot/tlpi
Cloning into '/var/lib/mock/f40-build-2488197-61651/root/chroot_tmpdir/scmroot/tlpi'...
$ git fetch origin 2c21c66af616c473b899ee019fd332ed9ea3cf9d:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/tlpi
 * [new ref]         2c21c66af616c473b899ee019fd332ed9ea3cf9d -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 2c21c66 Rebuild for new libgo (fedora#2264270)