Fix #3172 (Viewer crashes when opening LIT book)

src/calibre/debug.py

@@ -174,13 +174,6 @@ def main(args=sys.argv):
     elif opts.command:
         sys.argv = args[:1]
         exec opts.command
-    elif opts.exec_file:
-        sys.argv = args
-        base = os.path.dirname(os.path.abspath(opts.exec_file))
-        sys.path.insert(0, base)
-        g = globals()
-        g['__name__'] = '__main__'
-        execfile(opts.exec_file, g)
     elif opts.debug_device_driver:
         debug_device_driver()
     elif opts.migrate:

src/calibre/ebooks/oeb/reader.py

@@ -114,6 +114,8 @@ def _read_opf(self):
             except etree.XMLSyntaxError:
                 data = re.sub(r'(?is)<tours>.+</tours>', '', data)
                 self.logger.warn('OPF contains invalid tours section')
+                data = data.replace('<dc-metadata>',
+                    '<dc-metadata xmlns:dc="http://purl.org/metadata/dublin_core">')
                 opf = etree.fromstring(data)
 
         ns = namespace(opf.tag)