When listing a topic and its replies, the author is only obfuscated for the original post - author is not obfuscated on any replies.
This patch fixes it:
Index: tracdiscussion/templates/discussion-macros.html
===================================================================
--- tracdiscussion/templates/discussion-macros.html (revision 7214)
+++ tracdiscussion/templates/discussion-macros.html (working copy)
@@ -221,7 +221,7 @@
<div class="footer">
<div class="author">
- ${is_message_edit and discussion.author or message.author}
+ ${format_author(is_message_edit and discussion.author or message.author)}
</div>
<div class="time">
${is_message_edit and format_datetime(discussion.time) or format_datetime(message.time)} (${is_message_edit and pretty_timedelta(discussion.time) or pretty_timedelta(message.time)} ago)
