git-review-rebase: also flag changes in commit descriptions.

scripts/git-review-rebase/README.md

@@ -20,10 +20,15 @@ An interactive TUI (Terminal User Interface) tool for reviewing rebased git bran
   | ---- | ----------------------------------------- |
   | `=`  | Same commit (identical SHA1               |
   | `~`  | Loose match (same title, patchid changed) |
+  | `✎`  | Commit message changed                    |
   | `⤶`  | Already present in new upstream           |
   | `✗`  | Dropped during rebase                     |
   | `✚`  | Added in rebase                           |
 
+> A commit message comparison ignores trailing whitespace and surrounding blank lines, so `✎`
+> only shows up when the message content itself differs. It is never set on `=` matches, since
+> those commits are identical by definition.
+
 > **Patchid** is a checksum of a commit's diff (`git patch-id`). Two commits with different
 > SHA1 (e.g. after rebase) that introduce the same code changes will have the same patchid.
 > This allows the tool to match commits across a rebase even when their SHA-1s change.

scripts/git-review-rebase/src/git_review_rebase/commit_matching.py

@@ -6,7 +6,7 @@
 
 from .branch_range import BranchRange
 from .constants import CommitMatchInfoFlag
-from .git_utils import abbrev, commit_title
+from .git_utils import abbrev, commit_title, message_changed
 
 
 class RebasedCommitMatch:
@@ -67,6 +67,13 @@ def init_matches(self) -> None:
                 if right_commit is not None:
                     match_info = CommitMatchInfoFlag.LooseMatch
 
+            if (
+                right_commit is not None
+                and right_commit.id != left_commit.id
+                and message_changed(left_commit, right_commit)
+            ):
+                match_info |= CommitMatchInfoFlag.MessageChanged
+
             if (
                 right_commit is not None
                 and right_commit.id not in self.right_range._rebased_commits

scripts/git-review-rebase/src/git_review_rebase/constants.py

@@ -28,6 +28,7 @@ class SolarizedColors(StrEnum):
 class CommitMatchInfoFlag(Flag):
     SameCommit = auto()
     LooseMatch = auto()
+    MessageChanged = auto()
     PresentInRebaseOnto = auto()
     Dropped = auto()
     Added = auto()
@@ -49,6 +50,11 @@ def __init__(self, flag, character, definition):
         Text("~", SolarizedColors.Yellow),
         "Commit patchid has changed",
     ),
+    CommitMatchInfoFlag.MessageChanged: CommitMatchInfo(
+        CommitMatchInfoFlag.MessageChanged,
+        Text("✎", SolarizedColors.Orange),
+        "Commit message has changed",
+    ),
     CommitMatchInfoFlag.PresentInRebaseOnto: CommitMatchInfo(
         CommitMatchInfoFlag.PresentInRebaseOnto,
         Text("⤶", SolarizedColors.Blue),

scripts/git-review-rebase/src/git_review_rebase/git_utils.py

@@ -40,6 +40,16 @@ def commit_title(commit: pygit2.Commit) -> str:
     return (commit.message.splitlines() or [""])[0]
 
 
+def normalized_message(commit: pygit2.Commit) -> str:
+    """Commit message without trailing whitespace nor surrounding blank lines."""
+    return "\n".join(line.rstrip() for line in commit.message.strip().splitlines())
+
+
+def message_changed(left_commit: pygit2.Commit, right_commit: pygit2.Commit) -> bool:
+    """Return True if both commits do not share the same message."""
+    return normalized_message(left_commit) != normalized_message(right_commit)
+
+
 def cached_patchid_ref(revision: str) -> str:
     """Poor man's cache in git refs directly using merkle trees."""
     return f"refs/patchids/from_revision/" f"{revision[:2]}/{revision[2:4]}/{revision[4:]}"