Don't bail out of the cpplint cache is broken.

tools/presubmit.py

 #!/usr/bin/env python
 #
 # Copyright 2012 the V8 project authors. All rights reserved.
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 #       notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
@@ skipping 126 matching lines @@
   def __init__(self, sums_file_name):
     self.sums = {}
     self.sums_file_name = sums_file_name
 
   def Load(self):
     try:
       sums_file = None
       try:
         sums_file = open(self.sums_file_name, 'r')
         self.sums = pickle.load(sums_file)
-      except IOError:
-        # File might not exist, this is OK.
+      except:
+        # Cannot parse pickle for any reason. Not much we can do about it.
         pass
     finally:
       if sums_file:
         sums_file.close()
 
   def Save(self):
     try:
       sums_file = open(self.sums_file_name, 'w')
       pickle.dump(self.sums, sums_file)
+    except:
+      # Failed to write pickle. Try to clean-up behind us.
+      if sums_file:
+        sums_file.close()
+      try:
+        os.unlink(self.sums_file_name)
+      except:
+        pass
     finally:
       sums_file.close()
 
   def FilterUnchangedFiles(self, files):
     changed_or_new = []
     for file in files:
       try:
         handle = open(file, "r")
         file_sum = md5er(handle.read()).digest()
         if not file in self.sums or self.sums[file] != file_sum:
@@ skipping 258 matching lines @@
         "two empty lines between declarations check..."
   success = SourceProcessor().Run(workspace) and success
   if success:
     return 0
   else:
     return 1
 
 
 if __name__ == '__main__':
   sys.exit(Main())