Bug#1032105: pkg-perl-tools: [dpt prepare] gitddiff shouldn't use last tag but last tag in current branch

[Yadd]

Package: pkg-perl-tools
Version: 0.75
Severity: minor

Hi,

thanks for this powerful tool. When using `dpt prepare` on a package
that have backports, it shows the difference with last backport, not
last unstable upload. You can try for example with lemonldap-ng.

In lib/dpt-lib.sh, maybe you could replace

  TAG=$(git rev-list -n1 --tags)

by

  TAG=$(git describe | perl -pe 's/-\d+-\w+$//')

Cheers,
Yadd