Returns the more stringent rlimit value.  -1 means no limit.

def _rlimit_min(one_val, nother_val):
    """Returns the more stringent rlimit value.  -1 means no limit."""
    if one_val < 0 or nother_val < 0 :
        return max(one_val, nother_val)
    else:
        return min(one_val, nother_val)