Fix tests in PullRequestCreationViewModelTests

Not sure why branch in PullRequestCreationViewModel.Branches is coming
up null in unit test. Need to investigate.

Author: jcansdale

src/GitHub.App/ViewModels/GitHubPane/PullRequestCreationViewModel.cs

@@ -82,7 +82,8 @@ public PullRequestCreationViewModel(
                 .Where(_ => TargetBranch != null)
                 .Subscribe(x =>
                 {
-                    if (!x.Any(t => t.Equals(TargetBranch)))
+                    // HACK: Why is `t` null?
+                    if (!x.Any(t => t != null && t.Equals(TargetBranch)))
                     {
                         TargetBranch = GitHubRepository.IsFork ? GitHubRepository.Parent.DefaultBranch : GitHubRepository.DefaultBranch;
                     }

test/GitHub.App.UnitTests/ViewModels/GitHubPane/PullRequestCreationViewModelTests.cs

@@ -81,12 +81,12 @@ static TestData PrepareTestData(
 
         connection.HostAddress.Returns(HostAddress.Create("https://github.com"));
 
-        // this is the local repo instance that is available via TeamExplorerServiceHolder and friends
-        var activeRepo = Substitute.For<LocalRepositoryModel>();
-        activeRepo.LocalPath.Returns("");
-        activeRepo.Name.Returns(repoName);
-        activeRepo.CloneUrl.Returns(new UriString("http://github.com/" + sourceRepoOwner + "/" + repoName));
-        activeRepo.Owner.Returns(sourceRepoOwner);
+        var activeRepo = new LocalRepositoryModel
+        {
+            LocalPath = "",
+            Name = repoName,
+            CloneUrl = new UriString("http://github.com/" + sourceRepoOwner + "/" + repoName)
+        };
 
         Repository githubRepoParent = null;
         if (repoIsFork)