Default colours wrong after upgrading from 1.6.2 to 1.8.0

I have just upgraded from tin 1.6.2 to version 1.8.0.  It was all
fairly painless (and fixed my posting problem) however it's messed up
my default colours.

My standard xterm/rxvt uses a pale grey background (almost white) and
black text.

In my tinrc file I have:-
    col_normal=-1
    col_back=-1
but tin has set the background to black and the foreground to white
which is *not* what I want.  How do I get tin to leave these default
colours alone?

-- 
Chris Green ([email protected])

    "Never ascribe to malice that which can be explained by incompetence."