Prevent 6.3 from 'fixing' audio IDs in 6.4 custom covers (BL-15902)

src/BloomExe/Book/Book.cs

@@ -1273,6 +1273,13 @@ private void FixDuplicateAudioIdsInDataDiv(HtmlDom bookDOM, HashSet<string> idSe
                 return; // shouldn't happen, but paranoia sometimes pays off, especially in running tests.
             var nodes = dataDiv
                 .SafeSelectNodes("(.//div|.//span)[@id and contains(@class,'audio-sentence')]")
+                // We expect the customCover to have copies of other stuff in the data div.
+                .Where(x =>
+                    !(
+                        x is SafeXmlElement e
+                        && e.ParentWithAttributeValue("data-book", "customCover") != null
+                    )
+                )
                 .ToList();
             var duplicateAudioIdsFixed = 0;
             foreach (var audioElement in nodes)
@@ -1283,6 +1290,7 @@ private void FixDuplicateAudioIdsInDataDiv(HtmlDom bookDOM, HashSet<string> idSe
                 {
                     var newId = FixDuplicateAudioId(audioElement, id);
                     idSet.Add(newId);
+                    duplicateAudioIdsFixed++;
                 }
             }
             // OK, now fix all the places any duplicates were used in the book's pages.

src/BloomExe/SafeXml/SafeXmlElement.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Xml;
@@ -201,6 +201,30 @@ public SafeXmlElement ParentOrSelfWithClass(string targetClass)
             return current;
         }
 
+        public SafeXmlElement ParentWithAttribute(string targetAttribute)
+        {
+            var current = ParentElement;
+            while (current != null && !current.HasAttribute(targetAttribute))
+                current = current.ParentNode as SafeXmlElement;
+            return current;
+        }
+
+        /// <summary>
+        /// Get a parent element if any that has the specified value for the specified attribute
+        /// Note: currently if attrVal is empty it will match both parents where the attribute
+        /// is present and empty, and parents that don't have the attribute at all. It is not
+        /// intended that it should be used this way.
+        /// </summary>
+        public SafeXmlElement ParentWithAttributeValue(string targetAttribute, string attrVal)
+        {
+            ArgumentException.ThrowIfNullOrEmpty(attrVal);
+
+            var current = ParentElement;
+            while (current != null && current.GetAttribute(targetAttribute) != attrVal)
+                current = current.ParentNode as SafeXmlElement;
+            return current;
+        }
+
         public SafeXmlElement GetChildWithName(string name)
         {
             return ChildNodes.FirstOrDefault(n => n.Name.ToLowerInvariant() == name)