From 93c161e96f812c0ac885de850e0583bd83f6fd13 Mon Sep 17 00:00:00 2001
From: un-pogaz <46523284+un-pogaz@users.noreply.github.com>
Date: Mon, 24 Apr 2023 17:55:49 +0200
Subject: [PATCH] fix comments markdown

in v4, the switch to QtWebEngine introduced a bug where, in "HTML comments", paragraphs with a single <br> produced an visual extra gap in the render, problem will have been solved by using non-breaking space <p>&nbsp;</p>
(topic https://www.mobileread.com/forums/showthread.php?t=325991)

However, the "calibre.library.comments > markdown" still produces HTML with <p><br></p> causing the rendering of "Markdown comments" in Book Details (and Book Info) to still have this extra gap.
This commit is to fix this and do a more consistent rendering between "HTML comments" and "Markdown comments"
---
 src/calibre/library/comments.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/calibre/library/comments.py b/src/calibre/library/comments.py
index fe3853d656..1e312d5b5b 100644
--- a/src/calibre/library/comments.py
+++ b/src/calibre/library/comments.py
@@ -134,7 +134,8 @@ def markdown(val):
     except AttributeError:
         from calibre.ebooks.markdown import Markdown
         md = markdown.Markdown = Markdown()
-    return md.convert(val)
+    val = md.convert(val)
+    return re.sub(r'<p(|\s+[^>]*?)>\s*<br\s*/?>\s*</p>','<p\\1>\xa0</p>', val)
 
 
 def merge_comments(one, two):