superproject: Don't exit if superproject tag doesn't exist in manifest.

Don't exit if there are missing commit ids in superproject.

This change implements the following suggestion from delphij@:

"we should note the event (so we know that --use-superproject but there
 were some errors, e.g. manifest didn't specify commit id for some
 reason, or if there is no superproject but --use-superproject is
 used), print out a message telling the use that this is not support,
 but continue as if --no-use-superproject was specified?"

Changes:

superproject:
+ Added git_trace2_event_log as an argument to the constructor.
+ Sync method returns SyncResult a NamedTuple of
  ++ success - True if sync of superproject is successful, or False.
  ++ fatal - True if caller should exit, Or False.
+ UpdateProjectsRevisionId returns UpdateProjectsResult a NamedTuple of
   ++ manifest_path - path name of the overriding manifest file instead
      of None
   ++ fatal - True if caller should exit, Or False
+ _GetAllProjectsCommitIds returns CommitIdsResult a NamedTuple of
  ++ commit_ids - a dictionary with the projects/commit ids on success,
     otherwise None
  ++ fatal - True if caller should exit, Or False
+ Added  _SkipUpdatingProjectRevisionId a helper function to see if a
  project's revision id needs to be updated or not. This function is
  used to exclude projects from local manifest file.
+ Added the following error events into git_trace2_event_log
  ++ If superproject is missing in a manifest
  ++ If there are missing commit ids for projects.

command.py:
+ Deleted unused import - platform
+ Added git_trace2_event_log as a member so all subcmds can log error
  events.

main.py:
+ Initialized git_trace2_event_log as a member of command object.

init.py:
+ Deleted unused import - optparse

init.py:
+ Called sys.exit only if Sync returns exit=True

sync.py:
+ Called sys.exit only if Superproject's UpdateProjectsRevisionId returns
  exit=True
+ Reloaded the manifest only if manifest path is returned by
  UpdateProjectsRevisionId. If not, fall back to the old way of doing
  repo sync.

test_git_superproject:
+ Added code to verify error events are being logged.
+ Added a test for no superproject tag
+ Added test for UpdateProjectsRevisionId not updating the revision id
  with the commit ids.

Tested the code with the following commands.

+ Positive test case with aosp-master.
  $ repo_dev init -u persistent-https://android.git.corp.google.com/platform/manifest -b master --use-superproject
  NOTICE: --use-superproject is in beta; report any issues to the address described in `repo version`
  .../android/aosp/.repo/exp-superproject/925043f706ba64db713e9bf3b55987e2-superproject.git: Initial setup for superproject completed.

  Your identity is: Raman Tenneti <rtenneti@google.com>
  If you want to change this, please re-run 'repo init' with --config-name

  repo has been initialized in .../android/aosp

  $ repo_dev sync -j40 --use-superproject
  remote: Total 12 (delta 4), reused 12 (delta 4)
  NOTICE: --use-superproject is in beta; report any issues to the address described in `repo version`
  .../android/aosp/.repo/exp-superproject/925043f706ba64db713e9bf3b55987e2-superproject.git: Initial setup for superproject completed.
  ...
  repo sync has finished successfully.

+ Negative test case without superproject tag.
  $ repo_dev sync -j40 --use-superproject
  NOTICE: --use-superproject is in beta; report any issues to the address described in `repo version`
  repo error: superproject tag is not defined in manifest: .../android/aosp/.repo/manifest.xml
  error: Cannot get project commit ids from manifest
  error: Update of revsionId from superproject has failed. Please resync with --no-use-superproject option
  ...
  Checking out: 100% (1022/1022), done in 3.589s
  repo sync has finished successfully.

+ Test for missing commit_id for a project.
  $ repo_dev sync -j40 --use-superproject
  NOTICE: --use-superproject is in beta; report any issues to the address described in `repo version`
  .../android/aosp/.repo/exp-superproject/925043f706ba64db713e9bf3b55987e2-superproject.git: Initial setup for superproject completed.
  error: please file a bug using go/repo-bug to report missing commit_ids for: ['build/blueprint']
  error: Update of revsionId from superproject has failed. Please resync with --no-use-superproject option
  ...
  Checking out: 100% (1022/1022), done in 3.364s
  repo sync has finished successfully.

$ ./run_tests -v
  ...
  ...== 164 passed in 2.87s ==...

Bug: [google internal] b/189371541
Change-Id: I5ea49f87e8fa41be590fc0c914573e16c8cdfcfa
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/309162
Tested-by: Raman Tenneti <rtenneti@google.com>
Reviewed-by: Mike Frysinger <vapier@google.com>

subcmds/init.py

@@ -12,7 +12,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import optparse
 import os
 import platform
 import re
@@ -97,10 +96,13 @@ to update the working directory files.
     """
     superproject = git_superproject.Superproject(self.manifest,
                                                  self.repodir,
+                                                 self.git_event_log,
                                                  quiet=opt.quiet)
-    if not superproject.Sync():
+    sync_result = superproject.Sync()
+    if not sync_result.success:
       print('error: git update of superproject failed', file=sys.stderr)
-      sys.exit(1)
+      if sync_result.fatal:
+        sys.exit(1)
 
   def _SyncManifest(self, opt):
     m = self.manifest.manifestProject

subcmds/sync.py

@@ -302,21 +302,25 @@ later is required to fix a server side protocol bug.
       load_local_manifests: Whether to load local manifests.
 
     Returns:
-      Returns path to the overriding manifest file.
+      Returns path to the overriding manifest file instead of None.
     """
     superproject = git_superproject.Superproject(self.manifest,
                                                  self.repodir,
+                                                 self.git_event_log,
                                                  quiet=opt.quiet)
     all_projects = self.GetProjects(args,
                                     missing_ok=True,
                                     submodules_ok=opt.fetch_submodules)
-    manifest_path = superproject.UpdateProjectsRevisionId(all_projects)
-    if not manifest_path:
+    update_result = superproject.UpdateProjectsRevisionId(all_projects)
+    manifest_path = update_result.manifest_path
+    if manifest_path:
+      self._ReloadManifest(manifest_path, load_local_manifests)
+    else:
       print('error: Update of revsionId from superproject has failed. '
             'Please resync with --no-use-superproject option',
             file=sys.stderr)
-      sys.exit(1)
-    self._ReloadManifest(manifest_path, load_local_manifests)
+      if update_result.fatal:
+        sys.exit(1)
     return manifest_path
 
   def _FetchProjectList(self, opt, projects):
@@ -961,7 +965,9 @@ later is required to fix a server side protocol bug.
 
     load_local_manifests = not self.manifest.HasLocalManifests
     if self._UseSuperproject(opt):
-      manifest_name = self._UpdateProjectsRevisionId(opt, args, load_local_manifests)
+      new_manifest_name = self._UpdateProjectsRevisionId(opt, args, load_local_manifests)
+      if not new_manifest_name:
+        manifest_name = new_manifest_name
 
     if self.gitc_manifest:
       gitc_manifest_projects = self.GetProjects(args,