Fix --setup failing on fresh bare clones

- Set repositoryformatversion to 1 before enabling the
  extensions.relativeWorktrees v1 extension
- Use existing local branch when bare clone already created it
  instead of failing with "branch already exists"
- Pin install-local scripts to 0.0.0-local version to avoid
  pulling the published NuGet package

Author: ZeroErrors

install-local.ps1

@@ -3,4 +3,4 @@ dotnet tool uninstall -g git-wt 2>$null
 
 # Pack and install
 dotnet pack src/git-wt -o ./artifacts
-dotnet tool install -g --add-source ./artifacts git-wt
+dotnet tool install -g --add-source ./artifacts --version "0.0.0-local" git-wt

install-local.sh

@@ -6,4 +6,4 @@ dotnet tool uninstall -g git-wt 2>/dev/null || true
 
 # Pack and install
 dotnet pack src/git-wt -o ./artifacts
-dotnet tool install -g --add-source ./artifacts git-wt
+dotnet tool install -g --add-source ./artifacts --version "0.0.0-local" git-wt

src/git-wt/Commands.cs

@@ -121,9 +121,12 @@ public static int Setup(string remoteUrl)
         Console.WriteLine($"Creating worktree for '{defaultBranch}'...");
 
         int wtExit;
+        var localBranchExists = Git.Run(bareDir, "rev-parse", "--verify", $"refs/heads/{defaultBranch}").ExitCode == 0;
         using (new RelativeWorktreeScope(bareDir))
         {
-            wtExit = Git.RunLive(bareDir, "worktree", "add", "--track", "-b", defaultBranch, worktreePath, $"origin/{defaultBranch}");
+            wtExit = localBranchExists
+                ? Git.RunLive(bareDir, "worktree", "add", worktreePath, defaultBranch)
+                : Git.RunLive(bareDir, "worktree", "add", "--track", "-b", defaultBranch, worktreePath, $"origin/{defaultBranch}");
         }
 
         if (wtExit != 0)

src/git-wt/Git.cs

@@ -119,13 +119,20 @@ static Process StartProcess(ProcessStartInfo psi)
 sealed class RelativeWorktreeScope : IDisposable
 {
     readonly string _gitDir;
+    readonly string? _previousRepoVersion;
     readonly bool _relExtWasEnabled;
     readonly bool _relPathWasEnabled;
 
     public RelativeWorktreeScope(string gitDir)
     {
         _gitDir = gitDir;
 
+        // extensions.relativeWorktrees requires repositoryformatversion = 1.
+        var (verExit, verOutput, _) = Git.Run(gitDir, "config", "--get", "core.repositoryformatversion");
+        _previousRepoVersion = verExit == 0 ? verOutput.Trim() : null;
+        if (_previousRepoVersion != "1")
+            Git.Run(gitDir, "config", "core.repositoryformatversion", "1");
+
         var (relExtExit, relExtOutput, _) = Git.Run(gitDir, "config", "--get", "extensions.relativeWorktrees");
         _relExtWasEnabled = relExtExit == 0 && relExtOutput.Trim().Equals("true", StringComparison.OrdinalIgnoreCase);
 
@@ -144,5 +151,13 @@ public void Dispose()
             Git.Run(_gitDir, "config", "--unset", "extensions.relativeWorktrees");
         if (!_relPathWasEnabled)
             Git.Run(_gitDir, "config", "--unset", "worktree.useRelativePaths");
+
+        if (_previousRepoVersion != "1")
+        {
+            if (_previousRepoVersion is not null)
+                Git.Run(_gitDir, "config", "core.repositoryformatversion", _previousRepoVersion);
+            else
+                Git.Run(_gitDir, "config", "--unset", "core.repositoryformatversion");
+        }
     }
 }