programs don't recognize proxy settings in environment

[Micha Feigin <michf@post.tau.ac.il>]

I seem to have a strange problem.
Programs that are supposed to be able to recognize the proxy settings
from the environment don't do it properly (such as aptitude).
For example:

export http_proxy=<proxy>
aptitude update

Doesn't work, however:

export http_proxy=<proxy>
http_proxy=$http_proxy aptitude update

Does work. Any ideas where I got the settings screwed up? (This also
happened with reportbug)
I am using latest unstable with bash

Thanx