Fix bug w/ lists collapsing into thematic breaks

Related-to: 18bc860.

Author: wooorm

lib/handle/list.js

@@ -63,8 +63,7 @@ export function list(node, parent, context) {
       // That are each the first child.
       context.indexStack[context.indexStack.length - 1] === 0 &&
       context.indexStack[context.indexStack.length - 2] === 0 &&
-      context.indexStack[context.indexStack.length - 3] === 0 &&
-      context.indexStack[context.indexStack.length - 4] === 0
+      context.indexStack[context.indexStack.length - 3] === 0
     ) {
       useDifferentMarker = true
     }

test/index.js

@@ -2690,7 +2690,19 @@ test('listItem', (t) => {
   t.equal(
     to(createList(createList(createList()))),
     '*   *   -\n',
-    'should use a different bullet for an empty list item in three lists'
+    'should use a different bullet for an empty list item in three lists (1)'
+  )
+
+  t.equal(
+    to({
+      type: 'list',
+      children: [
+        {type: 'listItem', children: []},
+        {type: 'listItem', children: [createList(createList())]}
+      ]
+    }),
+    '*\n\n*   *   -\n',
+    'should use a different bullet for an empty list item in three lists (2)'
   )
 
   t.equal(