clang-format.py lint fails in mci if files were deleted

 [2015/08/14 19:38:50.462] Exception in thread Thread-6:

 [2015/08/14 19:38:50.462] Traceback (most recent call last):

 [2015/08/14 19:38:50.462]   File "/usr/lib64/python2.6/threading.py", line 532, in __bootstrap_inner

 [2015/08/14 19:38:50.462]     self.run()

 [2015/08/14 19:38:50.462]   File "/usr/lib64/python2.6/threading.py", line 484, in run

 [2015/08/14 19:38:50.462]     self.__target(*self.__args, **self.__kwargs)

 [2015/08/14 19:38:50.462]   File "/data/mci/src/buildscripts/clang_format.py", line 342, in worker

 [2015/08/14 19:38:50.462]     ret = func(item)

 [2015/08/14 19:38:50.462]   File "/data/mci/src/buildscripts/clang_format.py", line 281, in lint

 [2015/08/14 19:38:50.462]     with open(file_name, 'r') as original_text:

 [2015/08/14 19:38:50.462] IOError: [Errno 2] No such file or directory: '/data/mci/src/src/mongo/s/catalog/legacy/config_upgrade_v6_to_v7.cpp'