Bug#34944: apt-get should not print progress on non-tty

[sam@debian.org]

Package: apt
Version: 0.3.2

When standard output is not a tty, apt-get should avoid printing the
progress status ("Reading Package Lists" and "Building Dependency Tree").
It looks ugly when used with less, for example in

  apt-get -s dist-upgrade 2>&1 | less

 Sam

-- System Information
Debian Release: potato
Kernel Version: Linux zaphod 2.2.1 #1 Fri Jan 29 16:35:05 CET 1999 i586 unknown

Versions of the packages apt depends on:
ii  libc6           2.1.1-0.1      GNU C Library: shared libraries
ii  libstdc++2.9    2.91.61-1      The GNU stdc++ library (egcs version)