Fix InvalidOperationException when paging through results and the total items on the page is less than the page size due to package version filtering.

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

@@ -93,10 +93,8 @@ namespace ICSharpCode.PackageManagement
 		public void ReadPackages()
 		{
 			allPackages = null;
-			pages.CollectionChanged -= PagesChanged;
 			SelectedPageNumber = 1;
 			UpdatePackageViewModels();
-			pages.CollectionChanged += PagesChanged;
 		}
 		
 		void PagesChanged(object sender, NotifyCollectionChangedEventArgs e)
@@ -107,9 +105,13 @@ namespace ICSharpCode.PackageManagement
 		
 		void UpdatePackageViewModels()
 		{
+			pages.CollectionChanged -= PagesChanged;
+			
 			IEnumerable<IPackage> packages = GetPackagesForSelectedPage();
 			pages.TotalItemsOnSelectedPage = packages.Count();
 			UpdatePackageViewModels(packages);
+			
+			pages.CollectionChanged += PagesChanged;
 		}
 		
 		IEnumerable<IPackage> GetPackagesForSelectedPage()

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

@@ -93,6 +93,52 @@ namespace PackageManagement.Tests
 			viewModel.Search();
 			
 			Assert.AreEqual(0, viewModel.PackageViewModels.Count);
-		}		
+		}
+		
+		[Test]
+		public void ShowNextPage_TwoObjectsWatchingForPagesCollectionChangedEventAndUserMovesToPageTwoAndFilteredPackagesReturnsLessThanExpectedPackagesDueToMatchingVersions_InvalidOperationExceptionNotThrownWhen()
+		{
+			CreateViewModel();
+			viewModel.PageSize = 2;
+			
+			var package1 = new FakePackage() {
+             	Id = "First",
+             	Description = "",
+             	Version = new Version(0, 1, 0, 0)
+            };
+			var package2 = new FakePackage() {
+				Id = "Secon",
+             	Description = "",
+				Version = new Version(0, 2, 0, 0)
+			};
+			var package3 = new FakePackage() {
+				Id = "Test",
+             	Description = "",
+				Version = new Version(0, 3, 0, 0)
+			};
+			var package4 = new FakePackage() {
+				Id = "Test",
+             	Description = "",
+				Version = new Version(0, 4, 0, 0)
+			};
+			var packages = new FakePackage[] {
+				package1, package2, package3, package4
+			};
+			
+			packageManagementService.FakeActivePackageRepository.FakePackages.AddRange(packages);
+			
+			viewModel.ReadPackages();
+			
+			bool collectionChangedEventFired = false;
+			viewModel.Pages.CollectionChanged += (sender, e) => collectionChangedEventFired = true;
+			viewModel.ShowNextPage();
+			
+			var expectedPackages = new FakePackage[] {
+				package4
+			};
+			
+			PackageCollectionAssert.AreEqual(expectedPackages, viewModel.PackageViewModels);
+			Assert.IsTrue(collectionChangedEventFired);
+		}
 	}
 }