[libxml2] Don't add IDs in xmlSetTreeDoc

[Nick Wellnhofer <nwellnhof src gnome org>]

commit 220a7baeeee484bbd356a506f23deb57c57e0056
Author: Nick Wellnhofer <wellnhofer aevum de>
Date:   Tue Dec 23 21:28:37 2014 +0100

    Don't add IDs in xmlSetTreeDoc
    
    This partially reverts my previous commit fixing bug #741919.

 tree.c |    8 ++++++++
 1 files changed, 8 insertions(+), 0 deletions(-)
---
diff --git a/tree.c b/tree.c
index c6323b4..6a158ce 100644
--- a/tree.c
+++ b/tree.c
@@ -2806,11 +2806,19 @@ xmlSetTreeDoc(xmlNodePtr tree, xmlDocPtr doc) {
                prop->doc = doc;
                xmlSetListDoc(prop->children, doc);
 
+                /*
+                 * TODO: ID attributes should be also added to the new
+                 * document, but this breaks things like xmlReplaceNode.
+                 * The underlying problem is that xmlRemoveID is only called
+                 * if a node is destroyed, not if it's unlinked.
+                 */
+#if 0
                 if (xmlIsID(doc, tree, prop)) {
                     xmlChar *idVal = xmlNodeListGetString(doc, prop->children,
                                                           1);
                     xmlAddID(NULL, doc, idVal, prop);
                 }
+#endif
 
                prop = prop->next;
            }