Fix versioning logic in ctest to get the correct latest version.

bin/ctest.py

 #!/usr/bin/python
 #
 # Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Wrapper for tests that are run on builders."""
 
 import fileinput
 import optparse
@@ skipping 75 matching lines @@
         Info('Replacing line %s with %s' % (line, new_line))
         redirect_file.write('%s\n' % new_line)
         continue
 
     # Line does not need to be modified.
     redirect_file.write(line)
 
   fileinput.close()
 
 
+def _GreaterVersion(version_a, version_b):
+  """Returns the higher version number of two version number strings."""
+  version_regex = re.compile('.*(\d+)\.(\d+)\.(\d+)\.(\d+).*')
+  version_a_tokens = version_regex.match(version_a).groups()
+  version_b_tokens = version_regex.match(version_b).groups()
+  for i in range(4):
+    (a, b) = (int(version_a_tokens[i]), int(version_b_tokens[i]))
+    if a != b:
+      if a > b: return version_a
+      return version_b
+  return version_a
+
+
 def GetLatestLinkFromPage(url, regex):
   """Returns the latest link from the given url that matches regex.
 
   Args:
     url: Url to download and parse.
     regex: Regular expression to match links against.
   """
   url_file = urllib.urlopen(url)
   url_html = url_file.read()
+
   url_file.close()
 
   # Parses links with versions embedded.
   url_parser = HTMLDirectoryParser(regex=regex)
   url_parser.feed(url_html)
-  return max(url_parser.link_list)
+  return reduce(_GreaterVersion, url_parser.link_list)
 
 
 def GetNewestLinkFromZipBase(board, channel, zip_server_base):
   """Returns the url to the newest image from the zip server.
 
   Args:
     board: board for the image zip.
     channel: channel for the image zip.
     zip_server_base:  base url for zipped images.
   """
@@ skipping 159 matching lines @@
                    options.remote)
 
 
 if __name__ == '__main__':
   try:
     main()
   except Exception:
     print "Got exception."
     traceback.print_exc(file=sys.stdout)