Workaround libgit2/libgit2sharp#2037

Author: AArnott

test/Nerdbank.GitVersioning.Tests/VersionOracleTests.cs

@@ -604,16 +604,20 @@ public void Worktree_Support(bool detachedHead)
 
         string workTreePath = this.CreateDirectoryForNewRepo();
         Directory.Delete(workTreePath);
+        Worktree worktree;
         if (detachedHead)
         {
-            this.LibGit2Repository.Worktrees.Add("HEAD~1", "myworktree", workTreePath, isLocked: false);
+            worktree = this.LibGit2Repository.Worktrees.Add("HEAD~1", "myworktree", workTreePath, isLocked: false);
         }
         else
         {
             this.LibGit2Repository.Branches.Add("wtbranch", "HEAD~1");
-            this.LibGit2Repository.Worktrees.Add("wtbranch", "myworktree", workTreePath, isLocked: false);
+            worktree = this.LibGit2Repository.Worktrees.Add("wtbranch", "myworktree", workTreePath, isLocked: false);
         }
 
+        // Workaround for https://github.com/libgit2/libgit2sharp/issues/2037
+        Commands.Checkout(worktree.WorktreeRepository, "HEAD", new CheckoutOptions { CheckoutModifiers = CheckoutModifiers.Force });
+
         GitContext context = this.CreateGitContext(workTreePath);
         var oracleWorkTree = new VersionOracle(context);
         Assert.Equal(oracleOriginal.Version, oracleWorkTree.Version);