我最近试图从 ubuntu 12.10 更新，但我不断收到“无法获取”错误。
W: Failed to fetch
http://security.ubuntu.com/ubuntu/dists/quantal-security/Release
Unable to find expected entry 'independent/binary-amd64/Packages' in
Release file (Wrong sources.list entry or malformed file)
W: Failed to fetch
http://archive.ubuntu.com/ubuntu/dists/quantal/Release Unable to find
expected entry 'independent/source/Sources' in Release file (Wrong
sources.list entry or malformed file)
W: Failed to fetch
http://archive.ubuntu.com/ubuntu/dists/quantal-updates/Release Unable
to find expected entry 'independent/binary-amd64/Packages' in Release
file (Wrong sources.list entry or malformed file)
W: Failed to fetch
http://archive.ubuntu.com/ubuntu/dists/quantal-backports/Release
Unable to find expected entry 'independent/binary-amd64/Packages' in
Release file (Wrong sources.list …