use py3 compatible octal constants

tests/git_common_test.py

 #!/usr/bin/env python
 # Copyright 2013 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.
 
 """Unit tests for git_common.py"""
 
 import binascii
 import collections
 import os
@@ skipping 157 matching lines @@
 
   COMMIT_A = {
     'some/files/file1': {'data': 'file1'},
     'some/files/file2': {'data': 'file2'},
     'some/files/file3': {'data': 'file3'},
     'some/other/file':  {'data': 'otherfile'},
   }
 
   COMMIT_C = {
     'some/files/file2': {
-      'mode': 0755,
+      'mode': 0o0755,
       'data': 'file2 - vanilla\n'},
   }
 
   COMMIT_E = {
     'some/files/file2': {'data': 'file2 - merged\n'},
   }
 
   COMMIT_D = {
     'some/files/file2': {'data': 'file2 - vanilla\nfile2 - merged\n'},
   }
@@ skipping 554 matching lines @@
 
   COMMIT_A = {
     'some/files/file1': {'data': 'file1'},
     'some/files/file2': {'data': 'file2'},
     'some/files/file3': {'data': 'file3'},
     'some/other/file':  {'data': 'otherfile'},
   }
 
   COMMIT_C = {
     'some/files/file2': {
-      'mode': 0755,
+      'mode': 0o0755,
       'data': 'file2 - vanilla'},
   }
 
   COMMIT_E = {
     'some/files/file2': {'data': 'file2 - merged'},
   }
 
   COMMIT_D = {
     'some/files/file2': {'data': 'file2 - vanilla\nfile2 - merged'},
   }
@@ skipping 94 matching lines @@
                       self.repo.show_commit('A', format_string='%cn %ci'))
     self.assertEquals('Author McAuthorly 1970-01-03 00:00:00 +0000',
                       self.repo.show_commit('B', format_string='%an %ai'))
     self.assertEquals('Charles Committish 1970-01-04 00:00:00 +0000',
                       self.repo.show_commit('B', format_string='%cn %ci'))
 
 
 if __name__ == '__main__':
   sys.exit(coverage_utils.covered_main(
     os.path.join(DEPOT_TOOLS_ROOT, 'git_common.py')))