BeautifulSoup: Fix bug in extract() method that prevented extraction of identical individual tags

src/calibre/ebooks/BeautifulSoup.py

@@ -129,11 +129,16 @@ class PageElement:
 
     def extract(self):
         """Destructively rips this element out of the tree."""
+        # Changed by KG as list.remove uses _-eq__ which is True for two Tags
+        # with the same name and attributes.
         if self.parent:
-            try:
-                self.parent.contents.remove(self)
-            except ValueError:
-                pass
+            idx = None
+            for i, x in enumerate(self.parent.contents):
+                if x is self:
+                    idx = i
+                    break
+            if idx is not None:
+                self.parent.contents.pop(idx)
 
         #Find the two elements that would be next to each other if
         #this element (and any children) hadn't been parsed. Connect