Automate and document more of the release process.

RELEASE.md

 Upstream
 ========
 
-* update version in `configure.in`
+* prepare the environment:
 
-* update first line of `ChangeLog`
+        export VERSION=x.y.z
 
-* commit:
+* update `configure.in` and `ChangeLog`
 
-        git commit configure.in ChangeLog \
-            -m "Releasing backupninja $VERSION"
+        perl -pi -E \
+           "s{^AC_INIT\(\[backupninja\],\[[0-9.]+\],}{AC_INIT([backupninja],[$VERSION],}" \
+           configure.in && \
+        RELEASE_DATE=$(LC_ALL=C date '+%B %d, %Y') perl -pi -E \
+           "s{^version\s+[0-9.]+\s+--\s+UNRELEASED$}{version $VERSION -- $RELEASE_DATE}" \
+           ChangeLog
 
-* create the tarball:
+* commit, tag and create the tarball:
 
+        git commit configure.in ChangeLog \
+            -m "Releasing backupninja $VERSION" && \
+        git clean -fdx && \
         git tag -s "backupninja-$VERSION" \
-            -m "Releasing backupninja $VERSION"
-        ./autogen.sh
-        ./configure
+            -m "Releasing backupninja $VERSION" && \
+        ./autogen.sh && \
+        ./configure && \
         make dist
 
 * compare the content of the generated tarball with the content of the
   previous one
 
-* `mv backupninja-$VERSION.tar.gz ../tarballs/`
+* move the tarball outside of the Git working copy and clean up:
+
+        mkdir -p ../tarballs && \
+        mv backupninja-$VERSION.tar.gz ../tarballs/ && \
+        make distclean && \
+        git clean -fdx
 
-* cleanup: `make distclean`
+* Install (extract tarball, `.configure && make && sudo make install`)
+  and test.
+
+Debian
+======
 
-* sign the release:
+Prepare a new package:
 
-        cd ../tarballs
-        gpg --armor --detach-sign backupninja-$VERSION.tar.gz
+        git checkout debian && \
+        gbp import-orig --upstream-vcs-tag="backupninja-$VERSION" \
+            ../tarballs/backupninja-$VERSION.tar.gz && \
+        gbp dch --auto && \
+        dch -e && \
+        export DEBIAN_VERSION=$(dpkg-parsechangelog -SVersion) && \
+        git commit debian/changelog \
+           -m "Releasing backupninja ($DEBIAN_VERSION) to Debian unstable" && \
+        gbp buildpackage
 
-* upload the generated tarball and detached signature to
-  https://0xacab.org/riseuplabs/backupninja/
+Install the `.deb` and test.
 
-* push master branch and tags:
+Release
+=======
 
-        git push origin master --follow-tags
+* sign the release and push it to Git:
 
-* announce on the backupninja mailing-list
+        gpg --armor --detach-sign \
+            ../tarballs/backupninja-$VERSION.tar.gz && \
+        git checkout debian && \
+        gbp buildpackage --git-tag-only --git-sign-tags && \
+        git push --follow-tags origin \
+            master:master \
+            debian:debian \
+            pristine-tar:pristine-tar \
+            upstream:upstream
 
-Debian
-======
+* upload the upstream tarball and detached signature to the GitLab
+  milestone page with *Edit* → *Attach a file*
+* announce the release on the backupninja mailing-list,
+  pointing to the milestone web page
+* upload to Debian or ask someone listed in the `Uploaders` control
+  field to review and upload
 
-        ln -s backupninja-$VERSION.tar.gz backupninja_$VERSION.orig.tar.gz
-        cd ../git
-        git checkout debian
-        gbp import-orig --upstream-vcs-tag="backupninja-$VERSION" \
-            ../tarballs/backupninja-$VERSION.tar.gz
-        gbp dch --auto
-        dch -e
-        git commit debian/changelog -m "Releasing backupninja ($DEBIAN_VERSION) to Debian unstable"
-        git tag -s -m "Releasing backupninja ($DEBIAN_VERSION) to Debian unstable" backupninja_debian/$DEBIAN_VERSION
-        gbp buildpackage
+Open the next development cycle
+===============================
 
-* push the `debian` branch
-* publish the source package somewhere
-* ask someone listed in the `Uploaders` control field to review and upload
-* push the tag, once uploaded to Debian
+* `git checkout master`
+* Add an empty new section in `ChangeLog`, commit and push.