cabal-install sends invalid proxy password

[Dominic Steinitz]

Valery V. Vorotyntsev <valery.vv <at> gmail.com> writes:

> 
> Dear lazy programmers,
> 
> I was surprised to discover that `cabal-install' -- a popular utility
> for installing Hackage packages -- cannot work with HTTP proxies.
> Despite all the necessary code linked in.
> 
> `cabal update' command returns HTTP 407 (Proxy Authentication Required)
> error.  The problem is explained below and patches follow.
> 

I just tripped over the same problem yesterday so your patch saved me a lot of 
debugging.

Dominic.