bot_update: stop failing with a KeyError in the recipe on failure.

This has been low-key driving me bananas for a while, and I've seen
it confuse sheriffs etc many times.

Change-Id: If46ab55821447a3a70a3f0ea774c017f29fc7400
Reviewed-on: https://chromium-review.googlesource.com/c/1286819
Reviewed-by: Andrii Shyshkalov <tandrii@chromium.org>
Commit-Queue: John Budorick <jbudorick@chromium.org>

recipes/README.recipes.md

@@ -20,6 +20,7 @@
 
 **[Recipes](#Recipes)**
   * [bot_update:examples/full](#recipes-bot_update_examples_full)
+  * [bot_update:tests/ensure_checkout](#recipes-bot_update_tests_ensure_checkout)
   * [cipd:examples/full](#recipes-cipd_examples_full)
   * [cipd:examples/platform_suffix](#recipes-cipd_examples_platform_suffix)
   * [depot_tools:examples/full](#recipes-depot_tools_examples_full)
@@ -51,7 +52,7 @@ Recipe module to ensure a checkout is consistent on a bot.
 
 Wrapper for easy calling of bot_update.
 
-— **def [deapply\_patch](/recipes/recipe_modules/bot_update/api.py#409)(self, bot_update_step):**
+— **def [deapply\_patch](/recipes/recipe_modules/bot_update/api.py#411)(self, bot_update_step):**
 
 Deapplies a patch, taking care of DEPS and solution revisions properly.
     
@@ -67,7 +68,7 @@ Args:
   manifest_name: The name of the manifest to upload to LogDog.  This must
     be unique for the whole build.
 
-— **def [get\_project\_revision\_properties](/recipes/recipe_modules/bot_update/api.py#386)(self, project_name, gclient_config=None):**
+— **def [get\_project\_revision\_properties](/recipes/recipe_modules/bot_update/api.py#388)(self, project_name, gclient_config=None):**
 
 Returns all property names used for storing the checked-out revision of
 a given project.
@@ -884,6 +885,11 @@ Raises:
 [DEPS](/recipes/recipe_modules/bot_update/examples/full.py#5): [bot\_update](#recipe_modules-bot_update), [gclient](#recipe_modules-gclient), [gerrit](#recipe_modules-gerrit), [tryserver](#recipe_modules-tryserver), [recipe\_engine/buildbucket][recipe_engine/recipe_modules/buildbucket], [recipe\_engine/json][recipe_engine/recipe_modules/json], [recipe\_engine/path][recipe_engine/recipe_modules/path], [recipe\_engine/platform][recipe_engine/recipe_modules/platform], [recipe\_engine/properties][recipe_engine/recipe_modules/properties], [recipe\_engine/runtime][recipe_engine/recipe_modules/runtime]
 
 — **def [RunSteps](/recipes/recipe_modules/bot_update/examples/full.py#18)(api):**
+### *recipes* / [bot\_update:tests/ensure\_checkout](/recipes/recipe_modules/bot_update/tests/ensure_checkout.py)
+
+[DEPS](/recipes/recipe_modules/bot_update/tests/ensure_checkout.py#6): [bot\_update](#recipe_modules-bot_update), [gclient](#recipe_modules-gclient), [recipe\_engine/json][recipe_engine/recipe_modules/json]
+
+— **def [RunSteps](/recipes/recipe_modules/bot_update/tests/ensure_checkout.py#13)(api):**
 ### *recipes* / [cipd:examples/full](/recipes/recipe_modules/cipd/examples/full.py)
 
 [DEPS](/recipes/recipe_modules/cipd/examples/full.py#8): [cipd](#recipe_modules-cipd), [recipe\_engine/path][recipe_engine/recipe_modules/path], [recipe\_engine/platform][recipe_engine/recipe_modules/platform], [recipe\_engine/properties][recipe_engine/recipe_modules/properties], [recipe\_engine/step][recipe_engine/recipe_modules/step]

recipes/recipe_modules/bot_update/api.py

@@ -302,7 +302,9 @@ class BotUpdateApi(recipe_api.RecipeApi):
 
         # bot_update actually just sets root to be the folder name of the
         # first solution.
-        if result['did_run'] and 'checkout' not in self.m.path:
+        if (result.get('did_run')
+            and 'checkout' not in self.m.path
+            and 'root' in result):
           co_root = result['root']
           cwd = self.m.context.cwd or self.m.path['start_dir']
           self.m.path['checkout'] = cwd.join(*co_root.split(self.m.path.sep))

recipes/recipe_modules/bot_update/tests/ensure_checkout.py

@@ -0,0 +1,34 @@
+# Copyright 2018 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.
+
+from recipe_engine import post_process
+
+DEPS = [
+  'bot_update',
+  'gclient',
+  'recipe_engine/json',
+]
+
+
+def RunSteps(api):
+  api.gclient.set_config('depot_tools')
+  api.bot_update.ensure_checkout()
+
+
+def GenTests(api):
+  yield (
+      api.test('basic') +
+      api.post_process(post_process.StatusCodeIn, 0) +
+      api.post_process(post_process.DropExpectation)
+  )
+
+  yield (
+      api.test('failure') +
+      api.override_step_data(
+          'bot_update',
+          api.json.output({'did_run': True}),
+          retcode=1) +
+      api.post_process(post_process.StatusCodeIn, 1) +
+      api.post_process(post_process.DropExpectation)
+  )