Add simple tool to diff entries in lucene's CHANGES.txt that should be identical (#12860)

* add simple tool to diff entries in lucene's CHANGES.txt that should be identical

* remove temporary debugging code

dev-tools/scripts/diff_lucene_changes.py

@@ -0,0 +1,78 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to You 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.
+
+import os
+import re
+import subprocess
+import sys
+import tempfile
+import urllib.request
+
+'''
+A simple tool to see diffs between main's version of CHANGES.txt entries for
+a given release vs the stable branch's version.  It's best to keep these 1)
+identical and 2) matching what changes were actually backported to be honest
+to users and avoid future annoying conflicts on backport.
+'''
+
+# e.g. python3 -u diff_lucene_changes.py branch_9_9 main 9.9.0
+
+#
+
+def get_changes_url(branch_name):
+  if os.path.isdir(branch_name):
+    url = f'file://{branch_name}/lucene/CHANGES.txt'
+  else:
+    url = f'https://raw.githubusercontent.com/apache/lucene/{branch_name}/lucene/CHANGES.txt'
+  print(f'NOTE: resolving {branch_name} --> {url}')
+  return url
+
+def extract_release_section(changes_txt, release_name):
+  return re.search(f'=======+ Lucene {re.escape(release_name)} =======+(.*?)=======+ Lucene .*? =======+$',
+                   changes_txt.decode('utf-8'), re.MULTILINE | re.DOTALL).group(1).encode('utf-8')
+
+def main():
+  if len(sys.argv) < 3 or len(sys.argv) > 5:
+    print('\nUsage: python3 -u dev-tools/scripts/diff_lucene_changes.py <branch1-or-local-clone> <branch2-or-local-clone> <release-name> [diff-commandline-extras]\n')
+    print('  e.g.: python3 -u dev-tools/scripts/diff_lucene_changes.py branch_9_9 /l/trunk 9.9.0 "-w"\n')
+    sys.exit(1)
+
+  branch1 = sys.argv[1]
+  branch2 = sys.argv[2]
+  release_name = sys.argv[3]
+
+  if len(sys.argv) > 4:
+    diff_cl_extras = [sys.argv[4]]
+  else:
+    diff_cl_extras = []
+
+  branch1_changes = extract_release_section(urllib.request.urlopen(get_changes_url(branch1)).read(),
+                                            release_name)
+  branch2_changes = extract_release_section(urllib.request.urlopen(get_changes_url(branch2)).read(),
+                                            release_name)
+
+  with tempfile.NamedTemporaryFile() as f1, tempfile.NamedTemporaryFile() as f2:
+    f1.write(branch1_changes)
+    f2.write(branch2_changes)
+
+    command = ['diff'] + diff_cl_extras + [f1.name, f2.name]
+
+    # diff returns non-zero exit status when there are diffs, so don't pass check=True
+    print(subprocess.run(command, check=False, capture_output=True).stdout.decode('utf-8'))
+
+if __name__ == '__main__':
+  main()