Add default NuGet package source to NuGet.config file if no package sources exist.

src/AddIns/Misc/PackageManagement/Project/Src/RegisteredPackageSourceSettings.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Collections.Generic;
 using System.Collections.Specialized;
+using System.Linq;
 
 using NuGet;
 
@@ -59,6 +60,10 @@ namespace ICSharpCode.PackageManagement
 			var savedPackageSources = GetPackageSourcesFromSettings();
 			packageSources = new RegisteredPackageSources(savedPackageSources);
 			packageSources.CollectionChanged += PackageSourcesChanged;
+			
+			if (!savedPackageSources.Any()) {
+				UpdatePackageSourceSettingsWithChanges();
+			}
 		}
 		
 		IEnumerable<PackageSource> GetPackageSourcesFromSettings()

src/AddIns/Misc/PackageManagement/Test/Src/PackageManagementOptionsTests.cs

@@ -95,6 +95,26 @@ namespace PackageManagement.Tests
 			CollectionAssert.AreEqual(expectedSources, actualPackageSources);
 		}
 		
+		[Test]
+		public void PackageSources_NoPackageSourceInSavedSettings_DefaultPackageSourceAddedToSettings()
+		{
+			CreateSettings();
+			CreateOptions(fakeSettings);
+			
+			var packageSources = options.PackageSources;
+			
+			var defaultSource = RegisteredPackageSources.DefaultPackageSource;
+			
+			var expectedSavedPackageSourceSettings = new List<KeyValuePair<string, string>>();
+			string name = defaultSource.Name;
+			string sourceUrl = defaultSource.Source;
+			expectedSavedPackageSourceSettings.Add(new KeyValuePair<string, string>(name, sourceUrl));
+			
+			var actualSavedPackageSourceSettings = fakeSettings.GetValuesPassedToSetValuesForPackageSourcesSection();
+			
+			Assert.AreEqual(expectedSavedPackageSourceSettings, actualSavedPackageSourceSettings);
+		}
+		
 		[Test]
 		public void PackageSources_OnePackageSourceAdded_PackageSourceSavedInSettings()
 		{