Should have run apt-file before I submitted my last comment... When I run apt-file I get
# apt-file update E: Can't open /etc/apt/sources.list: No such file or directory since /etc/apt/sources.list doesn't exist on my host. The attached additional patch solves this problem for me and I think is the right approach. Regards, Andrew.
--- apt-file 2007-09-15 04:07:40.000000000 -0400 +++ apt-file 2007-09-15 04:22:42.000000000 -0400 @@ -114,7 +114,7 @@ my @files = ref $file ? @$file : ( $file ); - foreach $file (@files) { + foreach $file (grep -f, @files) { open(SOURCE, "< $file") || error "Can't open $file"; while(<SOURCE>) { next if /^\s*(?:$|\#|(?:deb-|rpm-))/xo;