The packaging is using Git Build Package, for extensive info, please see: https://wiki.debian.org/DanielKahnGillmor/preferred_packaging and the gbp documentation.

Git Repository

The sources for Debian packages are hosted at the official Debian repository located at https://salsa.debian.org/dns-team/bind9.git (for BIND 9.10, 9.11 and 9.12) and https://salsa.debian.org/dns-team/bind.git (for BIND 9.13+).

Access

To gain access to the Git repository, first create account here: https://signup.salsa.debian.org/ and then ask one of the existing maintainers to give you access to the repository (or the whole dns-team).

Updating the packages

The update if fairly simple if you know gbp, but for a quick TL;DR, do:

Enter the directory with gbp repository:

$ cd bind9

Import the new tarball using uscan

$ gbp import-orig --uscan
gbp:info: Launching uscan...
uscan: Newest version of bind on remote site is 9.13.6, local version is 9.13.5
uscan:    => Newer package available from
      https://ftp.isc.org/isc/bind9/9.13.6/bind-9.13.6.tar.gz
gpgv: Signature made Fri 08 Feb 2019 05:39:31 AM UTC
gpgv:                using RSA key BE0E9748B718253A28BB89FFF1B11BF05CF02E57
gpgv: Good signature from "Internet Systems Consortium, Inc. (Signing key, 2017-2018) <codesign@isc.org>"
gpgv: Signature made Fri 08 Feb 2019 05:39:32 AM UTC
gpgv:                using RSA key 156890685EA0DF6A1371EF2017CC5DB1F0088407
gpgv: Can't check signature: No public key
uscan warn: OpenPGP signature did not verify.
gbp:info: Using uscan downloaded tarball ../bind-9.13.6.tar.gz
What is the upstream version? [9.13.6] # <<< Hit ENTER here
gbp:info: Importing '../bind-9.13.6.tar.gz' to branch 'upstream' (filtering out ['.gitignore'])...
gbp:info: Source package is bind
gbp:info: Upstream version is 9.13.6
gbp:info: Replacing upstream source on 'master'
gbp:info: Successfully imported version 9.13.6 of ../bind-9.13.6.tar.gz

Rebase the patches for new release

$ gbp pq rebase
gbp:info: No pq branch found, importing patches
gbp:info: Trying to apply patches at '6e3038736612a13aedc58bd6f94745209771b7b8'
gbp:warning: Patch skip-rtld-deepbind-for-dyndb.diff failed to apply, retrying with whitespace fixup
gbp:error: Failed to apply '/home/ondrej/Projects/pkg-dns/bind/debian/patches/skip-rtld-deepbind-for-dyndb.diff': Error running git apply: error: patch failed: lib/dns/dyndb.c:133
error: lib/dns/dyndb.c: patch does not apply
gbp:error: Couldn't apply patches

If it fails, do it manually using quilt (<<< This is the only step really requiring manual intervention >>>)

$ while quilt push; do quilt refresh; done
Applying patch debian/patches/07_multiarch.diff
patching file isc-config.sh.in

Now at patch debian/patches/07_multiarch.diff
Refreshed patch debian/patches/07_multiarch.diff
Applying patch debian/patches/25_library_paths.diff
patching file lib/dns/Makefile.in
patching file lib/irs/Makefile.in
patching file lib/isc/Makefile.in
Hunk #1 succeeded at 107 (offset -2 lines).
Hunk #2 succeeded at 133 (offset -2 lines).
patching file lib/isccc/Makefile.in
Hunk #2 succeeded at 64 (offset -2 lines).
Hunk #3 succeeded at 82 (offset -2 lines).
patching file lib/isccfg/Makefile.in

Now at patch debian/patches/25_library_paths.diff
Refreshed patch debian/patches/25_library_paths.diff
Applying patch debian/patches/33_resource_missing_include.diff
patching file lib/isc/unix/resource.c

Now at patch debian/patches/33_resource_missing_include.diff
Refreshed patch debian/patches/33_resource_missing_include.diff
Applying patch debian/patches/75_ctxstart_no_sighandling.diff
patching file lib/isc/unix/app.c
Hunk #1 succeeded at 149 (offset -3 lines).

Now at patch debian/patches/75_ctxstart_no_sighandling.diff
Refreshed patch debian/patches/75_ctxstart_no_sighandling.diff
Applying patch debian/patches/80_reproducible_build.diff
patching file lib/dns/gen.c

Now at patch debian/patches/80_reproducible_build.diff
Refreshed patch debian/patches/80_reproducible_build.diff
Applying patch debian/patches/Add_--install-layout=deb_to_setup.py_call.patch
patching file bin/python/Makefile.in

Now at patch debian/patches/Add_--install-layout=deb_to_setup.py_call.patch
Refreshed patch debian/patches/Add_--install-layout=deb_to_setup.py_call.patch
Applying patch debian/patches/skip-rtld-deepbind-for-dyndb.diff
patching file lib/dns/dyndb.c
Hunk #1 FAILED at 133.
1 out of 1 hunk FAILED -- rejects in file lib/dns/dyndb.c
Patch debian/patches/skip-rtld-deepbind-for-dyndb.diff does not apply (enforce with -f)

Now enforce the patch and fix it or drop it if no longer needed

$ quilt push -f
Applying patch debian/patches/skip-rtld-deepbind-for-dyndb.diff
patching file lib/dns/dyndb.c
Hunk #1 FAILED at 133.
1 out of 1 hunk FAILED -- saving rejects to file lib/dns/dyndb.c.rej
Applied patch debian/patches/skip-rtld-deepbind-for-dyndb.diff (forced; needs refresh)
$ emacs lib/dns/dyndb.c.rej lib/dns/dyndb.c
$ quilt refresh
Refreshed patch debian/patches/skip-rtld-deepbind-for-dyndb.diff

Rinse and repeat until done:

$ while quilt push; do quilt refresh; done
File series fully applied, ends at patch debian/patches/skip-rtld-deepbind-for-dyndb.diff

Add the fixed patches to the repository and rebase then using gbp pq:

$ git commit -a -F - debian/patches << EOF
Rebase patches for BIND 9.13.6

Gbp-Dch: ignore
EOF
[master b78ec65c3] Rebase patches for BIND 9.13.6
 Date: Mon Feb 18 08:48:46 2019 +0000
 7 files changed, 30 insertions(+), 52 deletions(-)
$ gbp pq rebase
gbp:info: No pq branch found, importing patches
gbp:info: Trying to apply patches at 'b2d43c35ead0462861d3c994d1c30b146e6594a8'
gbp:info: 7 patches listed in 'debian/patches/series' imported on 'patch-queue/master'
gbp:info: Switching to 'patch-queue/master'
Current branch patch-queue/master is up to date.
$ gbp pq export
gbp:info: On 'patch-queue/master', switching to 'master'
gbp:info: Generating patches from git (master..patch-queue/master)
$ git commit --amend -a -F - debian/patches << EOF
Rebase patches for BIND 9.13.6

Gbp-Dch: ignore
EOF
[master caeea7f26] Rebase patches for BIND 9.13.6
 Date: Mon Feb 18 08:48:46 2019 +0000
 3 files changed, 11 insertions(+), 11 deletions(-)

Update and commit the changelog (this will start editor):

$ gbp dch -R -a -c
gbp:info: Changelog last touched at '5a7c095dc9d5463323dbb19108e38c86cb33c16d'
gbp:info: Changelog committed for version 1:9.13.6-1

Optionally, use a snapshot changelog (and use gbp dch -R -a -c when finished):

$ gbp dch -S -a -c
gbp:info: Changelog last touched at '5a7c095dc9d5463323dbb19108e38c86cb33c16d'
gbp:info: Changelog 1:9.13.6-1~1.gbpcaeea7 (snapshot #1) prepared up to caeea7f
gbp:info: Changelog committed for version 1:9.13.6-1~1.gbpcaeea7

Build the package using debuild in the local system:

$ gbp buildpackage --git-export-dir=/tmp/build --git-builder=debuild

When you confirmed the package builds, you can actually push the works to the repository and trigger the rebuilds for Ubuntu PPA and Debian DPA (https://bind.debian.net/bind/)