Avoid commits with duplicate names during v2 to v1 backport

.github/update-release-branch.py

@@ -239,20 +239,27 @@ def main():
   run_git('checkout', '-b', new_branch_name, ORIGIN + '/' + args.source_branch)
 
   if args.perform_v2_to_v1_backport:
+    # Migrate the package version number from a v2 version number to a v1 version number
     print(f'Setting version number to {version}')
-    subprocess.run(['npm', 'version', version])
-    run_git('add', 'package.json', 'package-lock.json', 'runner/package.json', 'runner/package-lock.json')
+    subprocess.run(['npm', 'version', version, '--no-git-tag-version'])
+    run_git('reset', 'HEAD~1')
+    run_git('add', 'package.json', 'package-lock.json')
 
+    # Migrate the changelog notes from v2 version numbers to v1 version numbers
     print('Migrating changelog notes from v2 to v1')
     subprocess.run(['sed', '-i', 's/## 2./## 1./g', 'CHANGELOG.md'])
+
+    # Amend the commit generated by `npm version` to update the CHANGELOG
+    run_git('add', 'CHANGELOG.md')
+    run_git('commit', '--amend', '-m', f'Update version and changelog for v{version}')
   else:
     # We don't need to do this for a v1 release, since the changelog has already been updated in the v2 branch.
     print('Updating changelog')
     update_changelog(version)
 
-  # Create a commit that updates the CHANGELOG
-  run_git('add', 'CHANGELOG.md')
-  run_git('commit', '-m', version)
+    # Create a commit that updates the CHANGELOG
+    run_git('add', 'CHANGELOG.md')
+    run_git('commit', '-m', f'Update changelog for v{version}')
 
   run_git('push', ORIGIN, new_branch_name)