Followup to https://codereview.chromium.org/1849113003

scripts/slave/recipes/infra/depot_tools_builder.py

 # Copyright 2015 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.
 
 """Recipe to build windows depot_tools bootstrap zipfile."""
 
 DEPS = [
   'recipe_engine/path',
   'recipe_engine/platform',
   'recipe_engine/properties',
   'recipe_engine/step',
 
   'depot_tools/git',
 
   'file',
   'gsutil',
   'zip',
 ]
 
 from recipe_engine.recipe_api import Property
 
 REPO_URL='https://chromium.googlesource.com/chromium/tools/depot_tools.git'
+DOC_UPLOAD_URL='gs://chrome-infra-docs/flat/depot_tools/docs/'
 
 PROPERTIES = {
   'revision': Property(
     kind=str, help='The revision of depot_tools to check out'),
 }
 
 def RunSteps(api, revision):
   # prepare the output dir and zip paths
   api.path['checkout'] = api.path['slave_build'].join('depot_tools')
   zip_out = api.path['slave_build'].join('depot_tools.zip')
 
-  # clean up any previous stuff
-  api.file.rmtree('rm depot_tools', api.path['checkout'])
-  api.file.remove('rm depot_tools.zip', zip_out, ok_ret=(0, 1))
+  with api.step.nest('clean workspace'):
+    api.file.rmtree('rm depot_tools', api.path['checkout'])
+    api.file.remove('rm depot_tools.zip', zip_out, ok_ret=(0, 1))
 
-  # generate the new directory
-  api.step('mk depot_tools', ['mkdir', api.path['checkout']])
+    # generate the new directory
+    api.step('mk depot_tools', ['mkdir', api.path['checkout']])
 
-  # clone + checkout depot_tools
-  api.git('clone', '--single-branch', '-n', REPO_URL, api.path['checkout'])
-  api.git('config', 'core.autocrlf', 'false', name='set autocrlf')
-  api.git('config', 'core.filemode', 'false', name='set filemode')
-  api.git('config', 'core.symlinks', 'false', name='set symlinks')
-  api.git('checkout', 'origin/master')
-  api.git('reset', '--hard',  revision)
-  api.git('reflog', 'expire', '--all')
-  api.git('gc', '--aggressive', '--prune=all')
+  with api.step.nest('clone + checkout'):
+    api.git('clone', '--single-branch', '-n', REPO_URL, api.path['checkout'])
+    api.git('config', 'core.autocrlf', 'false', name='set autocrlf')
+    api.git('config', 'core.filemode', 'false', name='set filemode')
+    api.git('config', 'core.symlinks', 'false', name='set symlinks')
+    api.git('checkout', 'origin/master')
+    api.git('reset', '--hard',  revision)
+    api.git('reflog', 'expire', '--all')
+    api.git('gc', '--aggressive', '--prune=all')
 
   # zip + upload repo
   api.zip.directory('zip it up', api.path['checkout'], zip_out)
   api.gsutil.upload(zip_out, 'chrome-infra', 'depot_tools.zip',
                     args=['-a', 'public-read'], unauthenticated_url=True)
 
   # upload html docs
   api.gsutil(['cp', '-r', '-z', 'html', '-a', 'public-read',
-              api.path['checkout'].join('man', 'html'),
-              'gs://chrome-infra-docs/flat/depot_tools/docs/'],
+              api.path['checkout'].join('man', 'html'), DOC_UPLOAD_URL],
              name='upload docs')
 
 
 def GenTests(api):
   yield api.test('basic') + api.properties(revision='deadbeef')