apt-cacher: failed to connect to libcurl

using instructions in <http://www.debuntu.org/how-to-set-up-a-repository-cache-with-apt-cacher>
$ dpkg --get-selections | grep curl
curl install
curlftpfs install
libcurl3 install
libcurl3-gnutls install
libwww-curl-perl install
python-pycurl install

$ cat /etc/apt/apt.conf
Acquire::http::Proxy "http://localhost:3142";
Acquire::http::Proxy::bugs.ubuntu.org "DIRECT";
Acquire::http::Proxy::bugs.debian.org "DIRECT";

# more /etc/apt/sources.list

deb http://localhost:3142 natty main restricted
deb-src http:localhost:3142 natty main restricted
deb http://localhost:3142 natty-updates main restricted
deb-src http://localhost:3142 natty-updates main restricted

# apt-get update
                                                                                    [a bunch of Ign lines ...]
Ign http://localhost natty-updates/restricted TranslationIndex
Err http://localhost natty/main amd64 Packages
  502 apt-cacher: failed to connect to libcurl
Err http://localhost natty/restricted amd64 Packages
  502 apt-cacher: failed to connect to libcurl
Err http://localhost natty/main Sources
  502 apt-cacher: failed to connect to libcurl
28% [Waiting for headers^C
#
A web search for "failed to connect to libcurl" gives nothing useful
I'd really like to get this working as I have a slew of virtual machines to install