$ git clone -n https://src.fedoraproject.org/rpms/perl-Test-Simple.git /var/lib/mock/f42-build-side-1-3499827-45966/root/chroot_tmpdir/scmroot/perl-Test-Simple
Cloning into '/var/lib/mock/f42-build-side-1-3499827-45966/root/chroot_tmpdir/scmroot/perl-Test-Simple'...
$ git fetch origin d4180fc69c2e91903a31ee3a0ab8674eaee8dfd6:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/perl-Test-Simple
 * [new ref]         d4180fc69c2e91903a31ee3a0ab8674eaee8dfd6 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at d4180fc Update to 1.302210