Add a recipe config to enable the bot_update "--with_tags" flag.

This is needed for release builders to checkout the release tags that
will be created when the buildspec branch/release info is migrated out
to the regular repos.

BUG=825063
R=jbudorick@google.com

Change-Id: I5f0e4cdd94de11c59f9b4a5c11aabea129e81523
Reviewed-on: https://chromium-review.googlesource.com/1036526
Reviewed-by: Andrii Shyshkalov <tandrii@chromium.org>
Commit-Queue: Michael Moss <mmoss@chromium.org>

recipes/README.recipes.md

@@ -742,7 +742,7 @@ like checkout or compile), and some of these tests have failed.
 
 [DEPS](/recipes/recipe_modules/gclient/examples/full.py#5): [gclient](#recipe_modules-gclient), [recipe\_engine/context][recipe_engine/recipe_modules/context], [recipe\_engine/path][recipe_engine/recipe_modules/path], [recipe\_engine/properties][recipe_engine/recipe_modules/properties], [recipe\_engine/step][recipe_engine/recipe_modules/step]
 
-— **def [RunSteps](/recipes/recipe_modules/gclient/examples/full.py#46)(api):**
+— **def [RunSteps](/recipes/recipe_modules/gclient/examples/full.py#47)(api):**
 ### *recipes* / [gclient:tests/patch\_project](/recipes/recipe_modules/gclient/tests/patch_project.py)
 
 [DEPS](/recipes/recipe_modules/gclient/tests/patch_project.py#9): [gclient](#recipe_modules-gclient), [recipe\_engine/properties][recipe_engine/recipe_modules/properties]

recipes/recipe_modules/bot_update/api.py

@@ -199,7 +199,7 @@ class BotUpdateApi(recipe_api.RecipeApi):
       cmd.append('--no_shallow')
     if with_branch_heads or cfg.with_branch_heads:
       cmd.append('--with_branch_heads')
-    if with_tags:
+    if with_tags or cfg.with_tags:
       cmd.append('--with_tags')
     if gerrit_no_reset:
       cmd.append('--gerrit_no_reset')

recipes/recipe_modules/gclient/config.py

@@ -94,6 +94,13 @@ def BaseConfig(USE_MIRROR=True, CACHE_DIR=None,
         required=False,
         hidden=True),
 
+    # Check out refs/tags.
+    with_tags = Single(
+        bool,
+        empty_val=False,
+        required=False,
+        hidden=True),
+
     disable_syntax_validation = Single(bool, empty_val=False, required=False),
 
     USE_MIRROR = Static(bool(USE_MIRROR)),
@@ -369,6 +376,10 @@ def infradata_master_manager(c):
 def with_branch_heads(c):
   c.with_branch_heads = True
 
+@config_ctx()
+def with_tags(c):
+  c.with_tags = True
+
 @config_ctx()
 def custom_tabs_client(c):
   soln = c.solutions.add()

recipes/recipe_modules/gclient/examples/full.py

@@ -40,6 +40,7 @@ TEST_CONFIGS = [
   'wasm_llvm',
   'webports',
   'with_branch_heads',
+  'with_tags',
 ]