When updating md5sum_bin, wipe the directory first

build/android/pylib/utils/md5sum_test.py

 #!/usr/bin/env python
 # Copyright 2014 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.
 
 import os
 import sys
 import unittest
 
 from pylib import cmd_helper
@@ skipping 195 matching lines @@
     device.adb.Push = mock.Mock()
     device_md5sum_output = [
         'WARNING: linker: /data/local/tmp/md5sum/md5sum_bin: '
             'unused DT entry: type 0x1d arg 0x15db',
         'THIS_IS_NOT_A_VALID_CHECKSUM_ZZZ some random text',
         '0123456789abcdeffedcba9876543210 '
             '/storage/emulated/legacy/test/file.dat',
     ]
     error = device_errors.AdbShellCommandFailedError('cmd', 'out', 2)
     device.RunShellCommand = mock.Mock(
-        side_effect=(error, device_md5sum_output))
+        side_effect=(error, '', device_md5sum_output))
 
     with mock.patch('os.path.getsize', return_value=1337):
       out = md5sum.CalculateDeviceMd5Sums(test_path, device)
       self.assertEquals(1, len(out))
       self.assertTrue('/storage/emulated/legacy/test/file.dat' in out)
       self.assertEquals('0123456789abcdeffedcba9876543210',
                         out['/storage/emulated/legacy/test/file.dat'])
-      self.assertEquals(2, len(device.RunShellCommand.call_args_list))
+      self.assertEquals(3, len(device.RunShellCommand.call_args_list))
       device.adb.Push.assert_called_once_with(
           'test/out/directory/md5sum_dist', '/data/local/tmp/md5sum/')
 
 
 if __name__ == '__main__':
   unittest.main(verbosity=2)