Fix #10121: html: <div> tag for admonition is not closed w/ docutils-…

…0.18

Since v0.18, docutils has output <aside> tag to represent admonitions.
On the other hand, our custom HTML Writer overrides the handler for
admonition nodes halfly.  As a result, the opening and closing tags
become mismatched.  This fully overrides the handler to use <div> tag to
represent admonitions.

sphinx/writers/html.py

@@ -14,7 +14,7 @@
 import re
 import urllib.parse
 import warnings
-from typing import TYPE_CHECKING, Iterable, Tuple, cast
+from typing import TYPE_CHECKING, Iterable, Optional, Tuple, cast
 
 from docutils import nodes
 from docutils.nodes import Element, Node, Text
@@ -285,6 +285,9 @@ def visit_admonition(self, node: Element, name: str = '') -> None:
             node.insert(0, nodes.title(name, admonitionlabels[name]))
         self.set_first_last(node)
 
+    def depart_admonition(self, node: Optional[Element] = None) -> None:
+        self.body.append('</div>\n')
+
     def visit_seealso(self, node: Element) -> None:
         self.visit_admonition(node, 'seealso')
 

sphinx/writers/html5.py

@@ -13,7 +13,7 @@
 import re
 import urllib.parse
 import warnings
-from typing import TYPE_CHECKING, Iterable, Set, Tuple, cast
+from typing import TYPE_CHECKING, Iterable, Optional, Set, Tuple, cast
 
 from docutils import nodes
 from docutils.nodes import Element, Node, Text
@@ -259,6 +259,9 @@ def visit_admonition(self, node: Element, name: str = '') -> None:
         if name:
             node.insert(0, nodes.title(name, admonitionlabels[name]))
 
+    def depart_admonition(self, node: Optional[Element] = None) -> None:
+        self.body.append('</div>\n')
+
     def visit_seealso(self, node: Element) -> None:
         self.visit_admonition(node, 'seealso')