enhance: save commit message to .git/MERGE_MSG while closing repo with in-progress state (#1795)

Signed-off-by: leo <longshuang@msn.cn>

Author: love-linger

src/ViewModels/Repository.cs

@@ -567,7 +567,11 @@ public void Close()
 
             if (!_isWorktree)
             {
-                _settings.LastCommitMessage = _workingCopy.CommitMessage;
+                if (_workingCopy.InProgressContext != null && !string.IsNullOrEmpty(_workingCopy.CommitMessage))
+                    File.WriteAllText(Path.Combine(GitDir, "MERGE_MSG"), _workingCopy.CommitMessage);
+                else
+                    _settings.LastCommitMessage = _workingCopy.CommitMessage;
+
                 using var stream = File.Create(Path.Combine(_gitCommonDir, "sourcegit.settings"));
                 JsonSerializer.Serialize(stream, _settings, JsonCodeGen.Default.RepositorySettings);
             }

src/ViewModels/WorkingCopy.cs

@@ -796,13 +796,8 @@ private void UpdateInProgressState()
                 if (LoadCommitMessageFromFile(Path.Combine(_repo.GitDir, "rebase-merge", "message")))
                     break;
 
-                var rebaseProcessingFile = Path.Combine(_repo.GitDir, "rebase-apply", "final-commit");
-                if (File.Exists(rebaseProcessingFile))
-                {
-                    var sha = File.ReadAllText(rebaseProcessingFile);
-                    if (!string.IsNullOrEmpty(sha))
-                        CommitMessage = new Commands.QueryCommitFullMessage(_repo.FullPath, sha).GetResult();
-                }
+                if (_inProgressContext is RebaseInProgress { StoppedAt: { } stopAt })
+                    CommitMessage = new Commands.QueryCommitFullMessage(_repo.FullPath, stopAt.SHA).GetResult();
             } while (false);
         }