$ git clone -n https://src.fedoraproject.org/rpms/golang-modernc-y.git /var/lib/mock/f40-build-2240435-53639/root/chroot_tmpdir/scmroot/golang-modernc-y
Cloning into '/var/lib/mock/f40-build-2240435-53639/root/chroot_tmpdir/scmroot/golang-modernc-y'...
$ git fetch origin bbc35cb88f735bfcb5bf9b34bc2f9f0a069e8523:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/golang-modernc-y
 * [new ref]         bbc35cb88f735bfcb5bf9b34bc2f9f0a069e8523 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at bbc35cb Initial import (fedora#2233180)