From 8206dd29669af3b4b9c1c58fea4837b0b8fb14d2 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Sun, 20 Apr 2025 09:05:07 +0530
Subject: [PATCH] Metadata review dialog: Fix merging of tags not working
 correctly

---
 src/calibre/gui2/metadata/diff.py | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/src/calibre/gui2/metadata/diff.py b/src/calibre/gui2/metadata/diff.py
index 008c38a438..92dca33ebd 100644
--- a/src/calibre/gui2/metadata/diff.py
+++ b/src/calibre/gui2/metadata/diff.py
@@ -562,11 +562,10 @@ class CompareSingle(QWidget):
     def merge_tags(self):
         widgets = self.widgets['tags']
         neww, oldw = widgets[:2]
-        val = oldw.value
-        lval = {icu_lower(x) for x in val}
-        extra = [x for x in neww.value if icu_lower(x) not in lval]
+        lval = {icu_lower(x) for x in neww.value}
+        extra = [x for x in oldw.value if icu_lower(x) not in lval]
         if extra:
-            neww.value = val + extra
+            neww.value += extra
 
     def merge_comments(self):
         widgets = self.widgets['comments']