parse errors in generic entityies are not properly reported

[Cardinal Kracker]

Somethings seems to be wrong with the parser when generic entities
are involved:

This program does not throw an error unless there is
also an error in the root document:

*** getloc.py
import sys, os
from lxml import etree
os.environ["XML_CATALOG_FILES"]="catalog.xml"
parser = etree.XMLParser(dtd_validation=True,load_dtd=True)
with open(sys.argv[1],"rb") as f:
  tree = etree.parse( f, parser )

*** book.dtd
<!ELEMENT book (chapter)* >
<!ELEMENT chapter (#PCDATA|b)* >
<!ELEMENT b (#PCDATA) >
<!ATTLIST chapter nr CDATA #REQUIRED >

*** catalog.xml
<?xml version="1.0"?>
<!DOCTYPE catalog PUBLIC "-//OASIS//DTD XML Catalogs V1.0//EN"
  "file:///usr/share/xml/schema/xml-core/catalog.dtd">
<catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog">
<public publicId="-//TEST//DTD BOOK//EN" uri="book.dtd"/>
</catalog>

*** part1.xml
<chapter nr="1">
<x/>
</chapter>
<chapter nr="2">
</chapter>

Running the program with this root document runs errorneously fine
*** book-a.xml
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE book PUBLIC "-//TEST//DTD BOOK//EN" "book.dtd" [
<!ENTITY part1 SYSTEM "part1.xml">
]>
<book>
&part1;
<chapter nr="3">
</chapter>

This one drops the error from part1:
*** book-b.xml
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE book PUBLIC "-//TEST//DTD BOOK//EN" "book.dtd" [
<!ENTITY part1 SYSTEM "part1.xml">
]>
<book>
&part1;
<chapter nr="3">
<z/>
</chapter>