$ git clone -n https://src.fedoraproject.org/rpms/golang-modernc-libc.git /var/lib/mock/f40-build-2240399-53637/root/chroot_tmpdir/scmroot/golang-modernc-libc
Cloning into '/var/lib/mock/f40-build-2240399-53637/root/chroot_tmpdir/scmroot/golang-modernc-libc'...
$ git fetch origin ff848e2786db2d9374b504851128c9b7cf135c93:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/golang-modernc-libc
 * [new ref]         ff848e2786db2d9374b504851128c9b7cf135c93 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at ff848e2 Initial import (fedora#2231393)