Use Merge instead of Amb on login control.

src/GitHub.App/ViewModels/LoginControlViewModel.cs

@@ -45,7 +45,7 @@ public LoginControlViewModel(
 
                 }).ToProperty(this, x => x.LoginMode);
 
-            AuthenticationResults = Observable.Amb(
+            AuthenticationResults = Observable.Merge(
                 loginToGitHubViewModel.Login,
                 EnterpriseLogin.Login);
             CancelCommand = ReactiveCommand.Create();

src/UnitTests/GitHub.App/ViewModels/LoginControlViewModelTests.cs

@@ -0,0 +1,49 @@
+using System;
+using System.Net;
+using System.Reactive.Linq;
+using System.Reactive.Subjects;
+using GitHub.Authentication;
+using GitHub.Info;
+using GitHub.Models;
+using GitHub.Primitives;
+using GitHub.Services;
+using GitHub.ViewModels;
+using NSubstitute;
+using Octokit;
+using ReactiveUI;
+using Xunit;
+
+public class LoginControlViewModelTests
+{
+    public class TheAuthenticationResultsCommand : TestBaseClass
+    {
+        [Fact]
+        public async void AllowsLoginFromEnterpriseAfterGitHubLoginHasFailed()
+        {
+            var repositoryHosts = Substitute.For<IRepositoryHosts>();
+
+            var gitHubLogin = Substitute.For<ILoginToGitHubViewModel>();
+            var gitHubLoginCommand = ReactiveCommand.CreateAsyncObservable(_ => 
+                Observable.Return(AuthenticationResult.CredentialFailure));
+            gitHubLogin.Login.Returns(gitHubLoginCommand);
+
+            var enterpriseLogin = Substitute.For<ILoginToGitHubForEnterpriseViewModel>();
+            var enterpriseLoginCommand = ReactiveCommand.CreateAsyncObservable(_ =>
+                Observable.Return(AuthenticationResult.Success));
+            enterpriseLogin.Login.Returns(enterpriseLoginCommand);
+
+            var loginViewModel = new LoginControlViewModel(repositoryHosts, gitHubLogin, enterpriseLogin);
+            var success = false;
+
+            loginViewModel.AuthenticationResults
+                .Where(x => x == AuthenticationResult.Success)
+                .Subscribe(_ => success = true);
+
+            await gitHubLoginCommand.ExecuteAsync();
+            await enterpriseLoginCommand.ExecuteAsync();
+
+            Assert.True(success);
+        }
+    }
+}
+

src/UnitTests/UnitTests.csproj

@@ -163,6 +163,7 @@
     <Compile Include="GitHub.App\Services\GitClientTests.cs" />
     <Compile Include="GitHub.App\Services\RepositoryCloneServiceTests.cs" />
     <Compile Include="GitHub.App\Services\RepositoryCreationServiceTests.cs" />
+    <Compile Include="GitHub.App\ViewModels\LoginControlViewModelTests.cs" />
     <Compile Include="GitHub.App\ViewModels\LoginToGitHubViewModelTests.cs" />
     <Compile Include="GitHub.App\ViewModels\RepositoryCloneViewModelTests.cs" />
     <Compile Include="GitHub.App\ViewModels\RepositoryCreationViewModelTests.cs" />