enhance: try to get stopped at revision info from .git/rebase-merge/head

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

Author: love-linger

src/Commands/QueryRevisionByRefName.cs

@@ -0,0 +1,21 @@
+namespace SourceGit.Commands
+{
+    public class QueryRevisionByRefName : Command
+    {
+        public QueryRevisionByRefName(string repo, string refname)
+        {
+            WorkingDirectory = repo;
+            Context = repo;
+            Args = $"rev-parse {refname}";
+        }
+
+        public string Result()
+        {
+            var rs = ReadToEnd();
+            if (rs.IsSuccess && !string.IsNullOrEmpty(rs.StdOut))
+                return rs.StdOut.Trim();
+
+            return null;
+        }
+    }
+}

src/ViewModels/InProgressContexts.cs

@@ -107,19 +107,24 @@ public RebaseInProgress(Repository repo) : base(repo.FullPath, "rebase")
         {
             _gitDir = repo.GitDir;
 
+            HeadName = File.ReadAllText(Path.Combine(repo.GitDir, "rebase-merge", "head-name")).Trim();
+            if (HeadName.StartsWith("refs/heads/"))
+                HeadName = HeadName.Substring(11);
+            else if (HeadName.StartsWith("refs/tags/"))
+                HeadName = HeadName.Substring(10);
+
             var stoppedSHAPath = Path.Combine(repo.GitDir, "rebase-merge", "stopped-sha");
+            var stoppedSHA = string.Empty;
             if (File.Exists(stoppedSHAPath))
-            {
-                var stoppedSHA = File.ReadAllText(stoppedSHAPath).Trim();
+                stoppedSHA = File.ReadAllText(stoppedSHAPath).Trim();
+            else
+                stoppedSHA = new Commands.QueryRevisionByRefName(repo.FullPath, HeadName).Result();
+
+            if (!string.IsNullOrEmpty(stoppedSHA))
                 StoppedAt = new Commands.QuerySingleCommit(repo.FullPath, stoppedSHA).Result() ?? new Models.Commit() { SHA = stoppedSHA };
-            }
 
             var ontoSHA = File.ReadAllText(Path.Combine(repo.GitDir, "rebase-merge", "onto")).Trim();
             Onto = new Commands.QuerySingleCommit(repo.FullPath, ontoSHA).Result() ?? new Models.Commit() { SHA = ontoSHA };
-
-            HeadName = File.ReadAllText(Path.Combine(repo.GitDir, "rebase-merge", "head-name")).Trim();
-            if (HeadName.StartsWith("refs/heads/"))
-                HeadName = HeadName.Substring(11);
         }
 
         public override bool Continue()