Print debugging information when svn info didn't return the URL

gclient_scm.py

 # Copyright (c) 2011 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.
 
 """Gclient-specific SCM-specific operations."""
 
 import logging
 import os
 import posixpath
 import re
@@ skipping 761 matching lines @@
       return
 
     # Get the existing scm url and the revision number of the current checkout.
     try:
       from_info = scm.SVN.CaptureInfo(os.path.join(self.checkout_path, '.'))
     except (gclient_utils.Error, subprocess2.CalledProcessError):
       raise gclient_utils.Error(
           ('Can\'t update/checkout %s if an unversioned directory is present. '
            'Delete the directory and try again.') % self.checkout_path)
 
+    if 'URL' not in from_info:
+      raise gclient_utils.Error(
+          ('gclient is confused. Couldn\'t get the url for %s.\n'
+           'Try using @unmanaged.\n%s') % (
+            self.checkout_path, from_info))
+
     # Look for locked directories.
     dir_info = scm.SVN.CaptureStatus(os.path.join(self.checkout_path, '.'))
     if any(d[0][2] == 'L' for d in dir_info):
       try:
         self._Run(['cleanup', self.checkout_path], options)
       except subprocess2.CalledProcessError, e:
         # Get the status again, svn cleanup may have cleaned up at least
         # something.
         dir_info = scm.SVN.CaptureStatus(os.path.join(self.checkout_path, '.'))
 
@@ skipping 180 matching lines @@
 
     This method returns a new list to be used as a command."""
     new_command = command[:]
     if revision:
       new_command.extend(['--revision', str(revision).strip()])
     # --force was added to 'svn update' in svn 1.5.
     if ((options.force or options.manually_grab_svn_rev) and
         scm.SVN.AssertVersion("1.5")[0]):
       new_command.append('--force')
     return new_command