apertis-pkg-merge-updates: always add the 'Sync from $UPSTREAM' message

This message is also required when a maintainer has to summarize the remaining Apertis changes. Thus, always add this message to save their time.

Edit: This change is because I'm lazy to have to manually write the same thing over and over

tools/apertis-pkg-merge-updates

@@ -146,20 +146,22 @@ def main():
     sys.exit(1)
 
   o = git('diff', '--exit-code', args.upstream, ':!debian/changelog', ':!debian/apertis/*', _ok_code=[0,1])
+  msg = [f'Sync from {args.upstream}.']
   if o.exit_code == 1:
     # we carry some changes in addition to changelog entries
     # and metadata under debian/apertis, so someone should
     # re-summarize the remaining changes
     version = upstream_version.full_version + args.local_suffix + '1'
+    msg.insert(0,'PLEASE SUMMARIZE remaining Apertis changes')
+    msg.append("Remaining Apertis specific changes:")
     bump_version(
         version,
         args.osname,
-        ['PLEASE SUMMARIZE remaining Apertis changes'],
+        msg,
         release=False
     )
   else:
     # no changes, but we add a suffix anyway
-    msg = [f'Sync from {args.upstream}.']
     if rebased_commits:
         msg.append(f"Rebase changes from {rebase_range}.")
     version = upstream_version.full_version + args.local_suffix + '0'