Improve the setup logic for tryserver

If the given change does not have a valid gerrit host name, stop
initializing the tryserver module.
Also polished the variable name and docstr added in crrev/c/2528670.

Recipe-Nontrivial-Roll: infra
Bug:1146487
Change-Id: I38193b25d37c724fd41d898eb020237fbf7cecdf
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2544000
Commit-Queue: Xinan Lin <linxinan@chromium.org>
Reviewed-by: Nodir Turakulov <nodir@chromium.org>
Reviewed-by: Andrii Shyshkalov <tandrii@google.com>

recipes/README.recipes.md

@@ -63,7 +63,7 @@ Wrapper for easy calling of bot_update.
 Deapplies a patch, taking care of DEPS and solution revisions properly.
     
 
-— **def [ensure\_checkout](/recipes/recipe_modules/bot_update/api.py#71)(self, gclient_config=None, suffix=None, patch=True, update_presentation=True, patch_root=None, with_branch_heads=False, with_tags=False, no_fetch_tags=False, refs=None, patch_oauth2=None, oauth2_json=None, use_site_config_creds=None, clobber=False, root_solution_revision=None, rietveld=None, issue=None, patchset=None, gerrit_no_reset=False, gerrit_no_rebase_patch_ref=False, accept_buildbucket_input=True, disable_syntax_validation=False, patch_refs=None, ignore_input_commit=False, add_blamelists=False, set_output_commit=False, step_test_data=None, enforce_fetch=False, \*\*kwargs):**
+— **def [ensure\_checkout](/recipes/recipe_modules/bot_update/api.py#71)(self, gclient_config=None, suffix=None, patch=True, update_presentation=True, patch_root=None, with_branch_heads=False, with_tags=False, no_fetch_tags=False, refs=None, patch_oauth2=None, oauth2_json=None, use_site_config_creds=None, clobber=False, root_solution_revision=None, rietveld=None, issue=None, patchset=None, gerrit_no_reset=False, gerrit_no_rebase_patch_ref=False, accept_input_gerrit_changes=True, disable_syntax_validation=False, patch_refs=None, ignore_input_commit=False, add_blamelists=False, set_output_commit=False, step_test_data=None, enforce_fetch=False, \*\*kwargs):**
 
 Args:
   * gclient_config: The gclient configuration to use when running bot_update.
@@ -90,11 +90,11 @@ Args:
     Use test_api.output_json to generate test data.
   * enforce_fetch: Enforce a new fetch to refresh the git cache, even if the
     solution revision passed in already exists in the current git cache.
-  * accept_buildbucket_input: should get the patchset from
-    buildbucket.build.input.gerrit_changes. If True, the input size is
-    asserted to be one, because bot_update module ONLY supports one CL.
-    Users may specify a CL via tryserver.set_change() and explicitly set
-    this flag False.
+  * accept_input_gerrit_changes: if True, get the patchset from
+    self.m.buildbucket.build.input.gerrit_changes, with an assertion that
+    the size of self.m.buildbucket.build.input.gerrit_changes is one,
+    because bot_update module ONLY supports one change. Users may specify a
+    change via tryserver.set_change() and explicitly set this flag False.
 
 — **def [get\_project\_revision\_properties](/recipes/recipe_modules/bot_update/api.py#506)(self, project_name, gclient_config=None):**
 
@@ -869,7 +869,7 @@ Returns true iff we have a change to check out.
 Set the gerrit change for this module.
 
 Args:
-  * cl: a GerritChange object.
+  * change: a self.m.buildbucket.common_pb2.GerritChange.
 
 — **def [set\_compile\_failure\_tryjob\_result](/recipes/recipe_modules/tryserver/api.py#196)(self):**
 

recipes/recipe_modules/bot_update/api.py

@@ -88,7 +88,7 @@ class BotUpdateApi(recipe_api.RecipeApi):
                       patchset=None,
                       gerrit_no_reset=False,
                       gerrit_no_rebase_patch_ref=False,
-                      accept_buildbucket_input=True,
+                      accept_input_gerrit_changes=True,
                       disable_syntax_validation=False,
                       patch_refs=None,
                       ignore_input_commit=False,
@@ -123,11 +123,11 @@ class BotUpdateApi(recipe_api.RecipeApi):
         Use test_api.output_json to generate test data.
       * enforce_fetch: Enforce a new fetch to refresh the git cache, even if the
         solution revision passed in already exists in the current git cache.
-      * accept_buildbucket_input: should get the patchset from
-        buildbucket.build.input.gerrit_changes. If True, the input size is
-        asserted to be one, because bot_update module ONLY supports one CL.
-        Users may specify a CL via tryserver.set_change() and explicitly set
-        this flag False.
+      * accept_input_gerrit_changes: if True, get the patchset from
+        self.m.buildbucket.build.input.gerrit_changes, with an assertion that
+        the size of self.m.buildbucket.build.input.gerrit_changes is one,
+        because bot_update module ONLY supports one change. Users may specify a
+        change via tryserver.set_change() and explicitly set this flag False.
     """
     assert use_site_config_creds is None, "use_site_config_creds is deprecated"
     assert rietveld is None, "rietveld is deprecated"
@@ -136,7 +136,7 @@ class BotUpdateApi(recipe_api.RecipeApi):
     assert patch_oauth2 is None, "patch_oauth2 is deprecated"
     assert oauth2_json is None, "oauth2_json is deprecated"
     assert not (ignore_input_commit and set_output_commit)
-    if accept_buildbucket_input:
+    if accept_input_gerrit_changes:
       assert len(self.m.buildbucket.build.input.gerrit_changes) <= 1, (
           'bot_update does not support more than one '
           'buildbucket.build.input.gerrit_changes')

recipes/recipe_modules/tryserver/api.py

@@ -261,12 +261,12 @@ class TryserverApi(recipe_api.RecipeApi):
     """Set the gerrit change for this module.
 
     Args:
-      * cl: a GerritChange object.
+      * change: a self.m.buildbucket.common_pb2.GerritChange.
     """
-    self._gerrit_info_initialized = False
-    self._gerrit_change = change
-    git_host = change.host
     gs_suffix = '-review.googlesource.com'
-    if git_host.endswith(gs_suffix):
-      git_host = '%s.googlesource.com' % git_host[:-len(gs_suffix)]
-    self._gerrit_change_repo_url = 'https://%s/%s' % (git_host, change.project)
+    if change.host.endswith(gs_suffix):
+      self._gerrit_info_initialized = False
+      self._gerrit_change = change
+      git_host = '%s.googlesource.com' % change.host[:-len(gs_suffix)]
+      self._gerrit_change_repo_url = 'https://%s/%s' % (git_host,
+                                                        change.project)