$ git clone -n https://src.fedoraproject.org/rpms/mercurial.git /var/lib/mock/f41-build-813940-148824/root/chroot_tmpdir/scmroot/mercurial
Cloning into '/var/lib/mock/f41-build-813940-148824/root/chroot_tmpdir/scmroot/mercurial'...
$ git fetch origin f4ed07c44046e84223a73e2e2bb97e7bfd2b1d5b:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/mercurial
 * [new ref]         f4ed07c44046e84223a73e2e2bb97e7bfd2b1d5b -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f4ed07c mercurial 6.8