[Release] Update merge script to leverage auto-tag bot

tools/release/merge_to_branch.py

Index: tools/release/merge_to_branch.py
diff --git a/tools/release/merge_to_branch.py b/tools/release/merge_to_branch.py
index 699fe1b3c66dbc5fc67970616eb811136ecad844..99bc2e26cac979763f46240ab1daa34e23ac8360 100755
--- a/tools/release/merge_to_branch.py
+++ b/tools/release/merge_to_branch.py
@@ -99,6 +99,12 @@ class SearchArchitecturePorts(Step):
 class CreateCommitMessage(Step):
   MESSAGE = "Create commit message."
 
+  def _create_commit_description(self, commit_hash):
+    patch_merge_desc = self.GitLog(n=1, format="%s", git_hash=commit_hash)
+    description = "Merged: " + patch_merge_desc + "\n"
+    description = description + "Hash: " + commit_hash + "\n\n"

[Michael Achenbach, 2015/10/21 12:32:35]

Maybe s/Hash/Revision

[Michael Hablich, 2015/10/21 12:41:26]

You mean like Hash: 4df56dsssss r12345

?

[Michael Achenbach, 2015/10/21 12:51:17]

No I mean literally. Use the more commonly used word "Revision" instead of
"Hash", so that'd read, e.g.:
Revision: 4df56dsssss

[Michael Hablich, 2015/10/22 14:25:50]

Acknowledged.

+    return description
+
   def RunStep(self):
 
     # Stringify: ["abcde", "12345"] -> "abcde, 12345"
@@ -107,17 +113,18 @@ class CreateCommitMessage(Step):
     if not self["revision_list"]:  # pragma: no cover
       self.Die("Revision list is empty.")
 
-    action_text = "Merged %s"
+    msg_pieces = []
 
-    # The commit message title is added below after the version is specified.
-    msg_pieces = [
-      "\n".join(action_text % s for s in self["full_revision_list"]),
-    ]
-    msg_pieces.append("\n\n")
+    if len(self["full_revision_list"]) > 1:
+      self["commit_title"] = "Merged: Squashed multiple commits."
+    else:
+      commit_hash = self["full_revision_list"][0]

[Michael Achenbach, 2015/10/21 12:32:35]

Why not make a pure cherry-pick in case of one commit?

[Michael Hablich, 2015/10/21 12:41:26]

I didn't want to introduce more complexity into the script especially as a pure
cherry-pick is offering no additional value.

[Michael Achenbach, 2015/10/21 12:51:17]

It offers the full original commit message instead of only a title. + this seems
to be the practice for chromium branches. I thought that should become the
standard case and squashing would be an exception.

On the other hand (have to think more): It might get harder for the v8rel script
to still refer to the merged CLs.

[Michael Hablich, 2015/10/22 14:25:49]

So, I tried cherry-picks on our branches a few times. My impression was that the
full commit message is only confusing and there is no mentioning what revision
got cherry-picked. I think a squash is much easier to digest and does not
introduce extra complexity into the script.

+      patch_merge_desc = self.GitLog(n=1, format="%s", git_hash=commit_hash)
+      title = "Merged: " + patch_merge_desc
+      self["commit_title"] = title
 
     for commit_hash in self["full_revision_list"]:
-      patch_merge_desc = self.GitLog(n=1, format="%s", git_hash=commit_hash)
-      msg_pieces.append("%s\n\n" % patch_merge_desc)
+      msg_pieces.append(self._create_commit_description(commit_hash))
 
     bugs = []
     for commit_hash in self["full_revision_list"]:
@@ -144,44 +151,11 @@ class ApplyPatches(Step):
     if self._options.patch:
       self.ApplyPatch(self._options.patch)
 
-
-class PrepareVersion(Step):
-  MESSAGE = "Prepare version file."
-
-  def RunStep(self):
-    # This is used to calculate the patch level increment.
-    self.ReadAndPersistVersion()
-
-
-class IncrementVersion(Step):
-  MESSAGE = "Increment version number."
-
-  def RunStep(self):
-    new_patch = str(int(self["patch"]) + 1)
-    if self.Confirm("Automatically increment V8_PATCH_LEVEL? (Saying 'n' will "
-                    "fire up your EDITOR on %s so you can make arbitrary "
-                    "changes. When you're done, save the file and exit your "
-                    "EDITOR.)" % VERSION_FILE):
-      text = FileToText(os.path.join(self.default_cwd, VERSION_FILE))
-      text = MSub(r"(?<=#define V8_PATCH_LEVEL)(?P<space>\s+)\d*$",
-                  r"\g<space>%s" % new_patch,
-                  text)
-      TextToFile(text, os.path.join(self.default_cwd, VERSION_FILE))
-    else:
-      self.Editor(os.path.join(self.default_cwd, VERSION_FILE))
-    self.ReadAndPersistVersion("new_")
-    self["version"] = "%s.%s.%s.%s" % (self["new_major"],
-                                       self["new_minor"],
-                                       self["new_build"],
-                                       self["new_patch"])
-
-
 class CommitLocal(Step):
   MESSAGE = "Commit to local branch."
 
   def RunStep(self):
     # Add a commit message title.
-    self["commit_title"] = "Version %s (cherry-pick)" % self["version"]
     self["new_commit_msg"] = "%s\n\n%s" % (self["commit_title"],
                                            self["new_commit_msg"])
     TextToFile(self["new_commit_msg"], self.Config("COMMITMSG_FILE"))
@@ -197,17 +171,6 @@ class CommitRepository(Step):
     self.GitPresubmit()
     self.vc.CLLand()
 
-
-class TagRevision(Step):
-  MESSAGE = "Create the tag."
-
-  def RunStep(self):
-    print "Creating tag %s" % self["version"]
-    self.vc.Tag(self["version"],
-                self.vc.RemoteBranch(self["merge_to_branch"]),
-                self["commit_title"])
-
-
 class CleanUp(Step):
   MESSAGE = "Cleanup."
 
@@ -276,12 +239,12 @@ class MergeToBranch(ScriptsBase):
       SearchArchitecturePorts,
       CreateCommitMessage,
       ApplyPatches,
-      PrepareVersion,
-      IncrementVersion,
+      # PrepareVersion,

[Michael Achenbach, 2015/10/21 12:32:35]

nit: Remove the comments.

[Michael Achenbach, 2015/10/21 12:38:37]

Done.

[Michael Hablich, 2015/10/21 12:41:26]

Done.

+      # IncrementVersion,
       CommitLocal,
       UploadStep,

[Michael Achenbach, 2015/10/21 12:32:35]

Maybe make the upload step configurable and let it add some text to the email
explaining the new merge script. Otherwise people might get confused.

[Michael Hablich, 2015/10/21 12:41:26]

I don't think more configuration will help. 

Adding a intermediate change announcement is a good idea though.

[Michael Achenbach, 2015/10/21 12:51:17]

I don't care how it would be done technically. But it would be nice if it ended
up in the email so that the merger and the reviewers see what's going on.

       CommitRepository,
-      TagRevision,
+      # TagRevision,
       CleanUp,
     ]