fix-crash-2.patch

diff --git a/hphp/runtime/ext/domdocument/ext_domdocument.cpp b/hphp/runtime/ext/domdocument/ext_domdocument.cpp
index 6a35725..3270d8a 100644
--- a/hphp/runtime/ext/domdocument/ext_domdocument.cpp
+++ b/hphp/runtime/ext/domdocument/ext_domdocument.cpp
@@ -2470,7 +2470,12 @@ Variant HHVM_METHOD(DOMNode, replaceChild,
       xmlReplaceNode(oldchild, newchild);
       dom_reconcile_ns(nodep->doc, newchild);
     }
-    return create_node_object(oldchild, data->doc(), false);
+
+    if (auto newchilddoc = domnewchildnode->doc_data()) {
+      removeOrphanIfNeeded(*newchilddoc->m_orphans, domnewchildnode->m_node);
+    }
+    return create_node_object(oldchild, data->doc(),
+                              oldchild->parent == nullptr);
   }

   php_dom_throw_error(NOT_FOUND_ERR, data->doc_data()->m_stricterror);