Look up a zonefile by txid
    Returns {'zonefile_hash': ..., 'name': ..., etc.}
    Returns None if not found

def atlasdb_get_zonefile_by_txid( txid, con=None, path=None ):
    """
    Look up a zonefile by txid
    Returns {'zonefile_hash': ..., 'name': ..., etc.}
    Returns None if not found
    """
    ret = None
    with AtlasDBOpen(con=con, path=path) as dbcon:

        sql = "SELECT * FROM zonefiles WHERE txid = ?;"
        args = (txid,)

        cur = dbcon.cursor()
        res = atlasdb_query_execute( cur, sql, args )

        for zfinfo in res:
            ret = {}
            ret.update(zfinfo)
            break

    return ret