Add a test to prove recent modification

- (Comments and PI as sibling)
- New nodes stay orphan.

README

@@ -1000,5 +1000,44 @@ does not work as bellow example. This is a known bug.
     <xupdate:remove xmlns:marshal="http://www.erp5.org/namespaces/marshaller" select="/object/local_permission[@id='View']/marshal:marshal/marshal:tuple/marshal:string[2]"/>
   </xupdate:modifications>
 
+30. Replace a node by another one following by a modification
+  >>> old_xml = """
+  ... <resource reference="Product Ballon de Plage a5962z">
+  ...   <title>Ballon de Plage</title>
+  ...   <reference>a5962z</reference>
+  ...   <sale_price>200.250000</sale_price>
+  ...   <purchase_price>100.250000</purchase_price>
+  ...   <category>ball_size/s4</category>
+  ...   <category>ball_size/s5</category>
+  ...   <category>colour/black</category>
+  ...   <category>colour/white</category>
+  ...   <category>type/product</category>
+  ... </resource>
+  ... """
+  >>> new_xml = """
+  ... <resource reference="Product Ballon de Plage a5962z">
+  ...   <title>Ballon de Plage</title>
+  ...   <reference>a5962z</reference>
+  ...   <sale_price>120.000000</sale_price>
+  ...   <ean13>1357913579130</ean13><!--replace purchase_price -->
+  ...   <category>ball_size/s4</category>
+  ...   <category>ball_size/s6</category><!--first modification to trig the bug -->
+  ...   <category>colour/red</category>
+  ...   <category>colour/white</category>
+  ...   <category>type/product</category>
+  ... </resource>
+  ... """
+  >>> erp5diff.compare(old_xml, new_xml)
+  >>> erp5diff.output()
+  <xupdate:modifications xmlns:xupdate="http://www.xmldb.org/xupdate" version="1.0">
+    <xupdate:update select="/resource/sale_price">120.000000</xupdate:update>
+    <xupdate:remove select="/resource/purchase_price"/>
+    <xupdate:update select="/resource/category[2]">ball_size/s6</xupdate:update>
+    <xupdate:update select="/resource/category[3]">colour/red</xupdate:update>
+    <xupdate:insert-before select="/resource/category[0]">
+      <xupdate:element name="ean13">1357913579130</xupdate:element>
+    </xupdate:insert-before>
+  </xupdate:modifications>
+
 - 2003-12-04, Yoshinori OKUJI <yo@nexedi.com>
 - 2009-09-15, Tatuya Kamada <tatuya@nexedi.com>