Revert "Forces to use trustable certificate."

This reverts commit 5ed93f4c.

slapos/libnetworkcache.py

@@ -220,17 +220,22 @@ class NetworkcacheClient(object):
       raise DirectoryNotFound('It was impossible to parse json response:\n%s'%
         traceback.format_exc())
     filtered_data_list = []
-    if self.signature_certificate_list is None:
-      raise DirectoryNotFound('No trustable certificate is configured.')
+    if self.signature_certificate_list is not None:
       for data in data_list:
         if len(data[1]):
           if self._verifySignatureInCertificateList(data[0], data[1]) and \
               self._isCompatible(data[0], binary_mode=binary_mode):
             filtered_data_list.append(data)
+    else:
+      filtered_data_list = data_list
 
     if len(filtered_data_list) == 0:
       raise DirectoryNotFound('Could not find a trustable entry.')
 
+    if len(filtered_data_list) > 1 and self.signature_certificate_list is None:
+      raise DirectoryNotFound('Too many entries for a given key %r. ' \
+               'Entries: %s.' % (key, str(data_list)))
+
     information_json, signature = filtered_data_list[0]
     try:
       information_dict = json.loads(information_json)