My last patch could remove /etc/network/interfaces file without checking if a backup exists. This seems not to be correct since the user could do this manually and then purge laptop-netconf which will remove interfaces and wont be able to retrieve the backup file. The corrected patch solve this issue.
Sorry for the inconvenience. Thanks Matheus Morais
--- debian/postrm 2007-09-12 10:34:03.000000000 -0300 +++ debian/postrm 2007-09-18 17:13:02.000000000 -0300 @@ -2,6 +2,10 @@ if [ "$1" = "purge" ]; then rm -f /etc/default/laptop-netconf + if [ -e /etc/network/interfaces.bak ]; then + rm -f /etc/network/interfaces + mv /etc/network/interfaces.bak /etc/network/interfaces + fi fi #DEBHELPER#