fix(dashboard.xaml.cs): 对于 SUBMODULE ，如果发现 HEAD 出于游离状态，这自动切换到找的第一个有效分支

SourceGit/Git/Repository.cs

@@ -927,7 +927,7 @@ namespace SourceGit.Git {
         public void UpdateSubmodule() {
             isWatcherDisabled = true;
 
-            var errs = RunCommand("submodule update", null);
+            var errs = RunCommand("submodule update --rebase --remote", null);
             if (errs != null) {
                 App.RaiseError(errs);
             } else {

SourceGit/UI/Dashboard.xaml.cs

@@ -204,6 +204,8 @@ namespace SourceGit.UI {
         }
 
         private void UpdateBranches(bool force = true) {
+            bool IsDetached = false;
+            Git.Branch branch = null;
             Task.Run(() => {
                 var branches = repo.Branches(force);
                 var remotes = repo.Remotes(true);
@@ -223,6 +225,7 @@ namespace SourceGit.UI {
                 foreach (var b in branches) {
                     if (b.IsLocal) {
                         MakeBranchNode(b, localBranchNodes, folders, states, "locals");
+                        branch = b;
                     } else if (!string.IsNullOrEmpty(b.Remote)) {
                         RemoteNode remote = null;
 
@@ -240,6 +243,10 @@ namespace SourceGit.UI {
                         }
 
                         MakeBranchNode(b, remote.Children, folders, states, "remotes");
+                    } else {
+                        /// 对于 SUBMODULE HEAD 出于游离状态（detached on commit id）
+                        /// 此时，分支既不是 本地分支，也不是远程分支
+                        IsDetached = b.IsCurrent;
                     }
                 }
 
@@ -264,6 +271,8 @@ namespace SourceGit.UI {
                     localBranchTree.ItemsSource = localBranchNodes;
                     remoteBranchTree.ItemsSource = remoteNodes;
                 });
+
+                if (IsDetached && branch != null) repo.Checkout(branch.Name);
             });
         }