gerrit_util is aware of auth errors

trychange.py

 #!/usr/bin/env python
 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Client-side script to send a try job to the try server. It communicates to
 the try server by either writting to a svn/git repository or by directly
 connecting to the server by HTTP.
 """
 
@@ skipping 761 matching lines @@
       except gerrit_util.GerritError, e:
         if e.http_status == 400:
           raise Error(e.reason)
         else:
           raise
 
   head_sha = scm.GIT.Capture(['log', '-1', '--format=%H'], cwd=os.getcwd())
 
   change_id = GetChangeId(head_sha)
 
-  # Check that the uploaded revision matches the local one.
-  changes = gerrit_util.GetChangeCurrentRevision(gerrit_host, change_id)
+  try:
+    # Check that the uploaded revision matches the local one.
+    changes = gerrit_util.GetChangeCurrentRevision(gerrit_host, change_id)
+  except gerrit_util.GerritAuthenticationError, e:
+    raise NoTryServerAccess(e.message)
+
   assert len(changes) <= 1, 'Multiple changes with id %s' % change_id
   if not changes:
     raise Error('A change %s was not found on the server. Was it uploaded?' %
                 change_id)
   logging.debug('Found Gerrit change: %s' % changes[0])
   if changes[0]['current_revision'] != head_sha:
     raise Error('Please upload your latest local changes to Gerrit.')
 
   # Post a try job.
   message = FormatMessage()
@@ skipping 454 matching lines @@
     return 1
   except (gclient_utils.Error, subprocess2.CalledProcessError), e:
     print >> sys.stderr, e
     return 1
   return 0
 
 
 if __name__ == "__main__":
   fix_encoding.fix_encoding()
   sys.exit(TryChange(None, None, False))