$ git clone -n https://src.fedoraproject.org/rpms/yp-tools.git /var/lib/mock/f42-build-3272233-41305/root/chroot_tmpdir/scmroot/yp-tools
Cloning into '/var/lib/mock/f42-build-3272233-41305/root/chroot_tmpdir/scmroot/yp-tools'...
$ git fetch origin a818b9fb6fc4969d6b885972fb3c5b73f790a6ea:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/yp-tools
 * [new ref]         a818b9fb6fc4969d6b885972fb3c5b73f790a6ea -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at a818b9f Add explicit BR: libxcrypt-devel