Fix numbering section at singlehtml mode does not work for nested toctree

sphinx/util/nodes.py

@@ -201,7 +201,8 @@ def inline_all_toctrees(builder, docnameset, docname, tree, colorfunc):
                 sof = addnodes.start_of_file(docname=includefile)
                 sof.children = subtree.children
                 for sectionnode in sof.traverse(nodes.section):
-                    sectionnode['docname'] = includefile
+                    if 'docname' not in sectionnode:
+                        sectionnode['docname'] = includefile
                 newnodes.append(sof)
         toctreenode.parent.replace(toctreenode, newnodes)
     return tree

tests/roots/test-tocdepth/bar.rst

@@ -11,10 +11,9 @@ Bar A
 
 should be 2.1
 
-Bar A1
+.. toctree::
-------
 
-should be 2.1.1
+   baz
 
 Bar B
 =====

tests/roots/test-tocdepth/baz.rst

@@ -0,0 +1,5 @@
+Baz A
+-----
+
+should be 2.1.1
+

tests/test_build_html.py

@@ -395,10 +395,12 @@ def test_tocdepth(app):
         'bar.html': [
             (".//h1", '2. Bar', True),
             (".//h2", '2.1. Bar A', True),
-            (".//h3", '2.1.1. Bar A1', True),
             (".//h2", '2.2. Bar B', True),
             (".//h3", '2.2.1. Bar B1', True),
         ],
+        'baz.html': [
+            (".//h1", '2.1.1. Baz A', True),
+        ],
     }
 
     for fname, paths in iteritems(expects):
@@ -438,9 +440,11 @@ def test_tocdepth_singlehtml(app):
             # bar.rst
             (".//h2", '2. Bar', True),
             (".//h3", '2.1. Bar A', True),
-            (".//h4", '2.1.1. Bar A1', True),
             (".//h3", '2.2. Bar B', True),
             (".//h4", '2.2.1. Bar B1', True),
+
+            # baz.rst
+            (".//h4", '2.1.1. Baz A', True),
         ],
     }