Use case insensitive comparison for determining which packages should be excluded from publishing

src/Tasks/Microsoft.NET.Build.Tasks/LockFileExtensions.cs

@@ -82,7 +82,7 @@ public static HashSet<string> GetPlatformExclusionList(
             LockFileTargetLibrary platformLibrary,
             IDictionary<string, LockFileTargetLibrary> libraryLookup)
         {
-            var exclusionList = new HashSet<string>();
+            var exclusionList = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
 
             exclusionList.Add(platformLibrary.Name);
             CollectDependencies(libraryLookup, platformLibrary.Dependencies, exclusionList);

src/Tasks/Microsoft.NET.Build.Tasks/ProjectContext.cs

@@ -37,7 +37,7 @@ public IEnumerable<LockFileTargetLibrary> GetRuntimeLibraries(IEnumerable<string
             Dictionary<string, LockFileTargetLibrary> libraryLookup =
                 runtimeLibraries.ToDictionary(e => e.Name, StringComparer.OrdinalIgnoreCase);
 
-            HashSet<string> allExclusionList = new HashSet<string>();
+            HashSet<string> allExclusionList = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
 
             if (IsPortable)
             {

test/Microsoft.NET.Publish.Tests/GivenThatWeWantToExcludeAPackageFromPublish.cs

@@ -0,0 +1,54 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using System.IO;
+using System.Runtime.InteropServices;
+using Microsoft.DotNet.Cli.Utils;
+using Microsoft.DotNet.InternalAbstractions;
+using Microsoft.NET.TestFramework;
+using Microsoft.NET.TestFramework.Assertions;
+using Microsoft.NET.TestFramework.Commands;
+using Xunit;
+using static Microsoft.NET.TestFramework.Commands.MSBuildTest;
+using System.Xml.Linq;
+
+namespace Microsoft.NET.Publish.Tests
+{
+    public class GivenThatWeWantToExcludeAPackageFromPublish : SdkTest
+    {
+        [Fact]
+        public void It_does_not_publish_a_PackageReference_with_PrivateAssets_All()
+        {
+            var helloWorldAsset = _testAssetsManager
+                .CopyTestAsset("HelloWorld", "PublishExcludePackage")
+                .WithSource()
+                .WithProjectChanges(project =>
+                {
+                    var ns = project.Root.Name.Namespace;
+
+                    var itemGroup = new XElement(ns + "ItemGroup");
+                    project.Root.Add(itemGroup);
+
+                    //  Using different casing for the package ID here, to test the scenario from https://github.com/dotnet/sdk/issues/376
+                    itemGroup.Add(new XElement(ns + "PackageReference", new XAttribute("Include", "NEWTONSOFT.Json"),
+                                                                        new XAttribute("Version", "9.0.1"),
+                                                                        new XAttribute("PrivateAssets", "All")));
+                })
+                .Restore();
+
+            var publishCommand = new PublishCommand(Stage0MSBuild, helloWorldAsset.TestRoot);
+            var publishResult = publishCommand.Execute();
+
+            publishResult.Should().Pass();
+
+            var publishDirectory = publishCommand.GetOutputDirectory();
+
+            publishDirectory.Should().OnlyHaveFiles(new[] {
+                "HelloWorld.dll",
+                "HelloWorld.pdb",
+                "HelloWorld.deps.json",
+                "HelloWorld.runtimeconfig.json"
+            });
+        }
+    }
+}