imgmath: Cleanup math dir in embed mode

sphinx/ext/imgmath.py

@@ -294,6 +294,19 @@ def cleanup_tempdir(app: Sphinx, exc: Exception) -> None:
         pass
 
 
+def cleanup_mathdir(app: Sphinx, exc: Exception) -> None:
+    if exc:
+        return
+    # in embed mode, the images are generated in the math output dir to be
+    # shared across workers, but are not useful to the document
+    if app.builder.config.imgmath_embed:
+        mathdir = path.join(app.builder.outdir, app.builder.imagedir, 'math')
+        try:
+            shutil.rmtree(mathdir)  # type: ignore
+        except Exception:
+            pass
+
+
 def get_tooltip(self: HTMLTranslator, node: Element) -> str:
     if self.builder.config.imgmath_add_tooltips:
         return ' alt="%s"' % self.encode(node.astext()).strip()
@@ -385,4 +398,5 @@ def setup(app: Sphinx) -> Dict[str, Any]:
     app.add_config_value('imgmath_font_size', 12, 'html')
     app.add_config_value('imgmath_embed', False, 'html', [bool])
     app.connect('build-finished', cleanup_tempdir)
+    app.connect('build-finished', cleanup_mathdir)
     return {'version': sphinx.__display_version__, 'parallel_read_safe': True}