Add python3 support to bot_update recipe module

Bug: 1227140
Change-Id: Id4938c966da54957f84f59d0aef0c68c381ad5f6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/3016032Reviewed-by: Josip Sokcevic <sokcevic@google.com>
Commit-Queue: Gavin Mak <gavinmak@google.com>

recipes/recipe_modules/bot_update/resources/bot_update.py

@@ -5,9 +5,9 @@
 
 # TODO(hinoka): Use logging.
 
+from __future__ import division
 from __future__ import print_function
 
-import cStringIO
 import codecs
 from contextlib import contextmanager
 import copy
@@ -18,19 +18,24 @@ import json
 import optparse
 import os
 import pprint
-import random
 import re
 import subprocess
 import sys
 import tempfile
 import threading
 import time
-import urllib2
-import urlparse
 import uuid
 
 import os.path as path
 
+# TODO(crbug.com/1227140): Clean up when py2 is no longer supported.
+try:
+  from cStringIO import StringIO
+  import urlparse
+except ImportError:  # pragma: no cover
+  from io import StringIO
+  import urllib.parse as urlparse
+
 # How many bytes at a time to read from pipes.
 BUF_SIZE = 256
 
@@ -170,7 +175,7 @@ def call(*args, **kwargs):  # pragma: no cover
   stdin_data = kwargs.pop('stdin_data', None)
   if stdin_data:
     kwargs['stdin'] = subprocess.PIPE
-  out = cStringIO.StringIO()
+  out = StringIO()
   new_env = kwargs.get('env', {})
   env = os.environ.copy()
   env.update(new_env)
@@ -455,7 +460,7 @@ def create_manifest():
         for path, info in json.load(f).items()
         if info['rev'] is not None
       }
-  except ValueError, SubprocessFailed:
+  except (ValueError, SubprocessFailed):
     return {}
   finally:
     os.remove(fname)
@@ -598,7 +603,7 @@ def _maybe_break_locks(checkout_path, tries=3):
             print('FAILED to break lock: %s: %s' % (to_break, ex))
             raise
 
-  for _ in xrange(tries):
+  for _ in range(tries):
     try:
       attempt()
       return