Convert a zip to a tar.gz
1. extract the zip # unzip -d . <file>.zip 2. repackage it as tar.gz # tar xzf <file>.tar.gz <dir_extracted>
or use some conversion tools, like http://effbot.org/zone/zip2tar.htm
repackage upstream tarball
If you do repackage, make sure to provide an get-orig-source target to retrieve (?), unpack, modify, and repack that (and the top level dir should have ".orig" appended).
check diff.gz for non-debian changes
zgrep '^--- ' <pkg>.diff.gz
optionally:
zgrep '^+++ ' <pkg>.diff.gz | grep -v /debian/