Add a script to update the debian changelog for non-Debian systems

changelog.d/10778.misc

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+Add a script to update the Debian changelog in a Docker container for systems that aren't Debian-based.

scripts-dev/update_debian_changelog.sh

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+#!/bin/bash -e
+# Copyright 2021 The Matrix.org Foundation C.I.C.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# This script is meant to be used inside a Docker container to run the `dch` incantations
+# needed to release Synapse. This is useful on systems like macOS where such scripts are
+# not easily accessible.
+#
+# Running it (when if the current working directory is the root of the Synapse checkout):
+#   docker run -v $PWD:/synapse ubuntu:latest /synapse/scripts-dev/update_debian_changelog.sh VERSION
+#
+# The image can be replaced by any other Debian-based image (as long as the `devscripts`
+# package exists in the default repository).
+# `VERSION` is the version of Synapse being released without the leading "v" (e.g. 1.42.0).
+
+# Check if a version was provided.
+if [ "$#" -ne 1 ]; then
+  echo "Usage: update_debian_changelog.sh VERSION"
+  echo "VERSION is the version of Synapse being released in the form 1.42.0 (without the leading \"v\")"
+  exit 1
+fi
+
+# We set -x here rather than in the shebang so that if we need to exit early because no
+# version was provided, the message doesn't get drowned in useless output.
+set -x
+
+# Make the root of the Synapse checkout the current working directory.
+cd /synapse
+
+# Update the packages list and install devscripts (which provides dch). We need to make
+# the Debian frontent noninteractive because installing devscripts otherwise asks for the
+# machine's location.
+apt-get update
+DEBIAN_FRONTEND=noninteractive apt-get install -y devscripts
+
+# Update the Debian changelog.
+ver=${1}
+dch -M -v $(sed -Ee 's/(rc|a|b|c)/~\1/' <<<$ver) "New synapse release $ver."
+dch -M -r -D stable ""