Re-implement conversion of 404 to DirectoryNotFound.

slapos/libnetworkcache.py

@@ -162,7 +162,12 @@ class NetworkcacheClient(object):
     file_descriptor = tempfile.NamedTemporaryFile()
     request = urllib2.Request(url=url, data=None,
       headers=self.shadir_header_dict)
-    data = urllib2.urlopen(request).read()
+    try:
+      data = urllib2.urlopen(request).read()
+    except urllib2.HTTPError, error:
+      if error.code == httplib.NOT_FOUND:
+        raise DirectoryNotFound('Directory not found at %s' % url)
+      raise
     # Filtering...
     data_list = json.loads(data)
     if len(data_list) > 1 and not \