Attempt to resolve workload gc bug

Author: Forgind

src/Cli/dotnet/commands/dotnet-workload/WorkloadUtilities.cs

@@ -0,0 +1,37 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using Microsoft.Deployment.DotNet.Releases;
+
+namespace Microsoft.DotNet.Workloads.Workload
+{
+    internal class WorkloadUtilities
+    {
+        internal static int VersionCompare(string first, string second)
+        {
+            if (first.Equals(second))
+            {
+                return 0;
+            }
+
+            var firstDash = first.IndexOf('-');
+            var secondDash = second.IndexOf('-');
+            firstDash = firstDash < 0 ? first.Length : firstDash;
+            secondDash = secondDash < 0 ? second.Length : secondDash;
+
+            var firstVersion = new Version(first.Substring(0, firstDash));
+            var secondVersion = new Version(second.Substring(0, secondDash));
+
+            var comparison = firstVersion.CompareTo(secondVersion);
+            if (comparison != 0)
+            {
+                return comparison;
+            }
+
+            var modifiedFirst = "1.1.1" + (firstDash == first.Length ? string.Empty : first.Substring(firstDash));
+            var modifiedSecond = "1.1.1" + (secondDash == second.Length ? string.Empty : second.Substring(secondDash));
+
+            return new ReleaseVersion(modifiedFirst).CompareTo(new ReleaseVersion(modifiedSecond));
+        }
+    }
+}

src/Cli/dotnet/commands/dotnet-workload/install/WorkloadGarbageCollector.cs

@@ -115,7 +115,7 @@ void GarbageCollectWorkloadSets()
                 //  If there isn't a rollback state file, don't garbage collect the latest workload set installed for the feature band
                 if (installedWorkloadSets.Any())
                 {
-                    var latestWorkloadSetVersion = installedWorkloadSets.Keys.MaxBy(k => new ReleaseVersion(k));
+                    var latestWorkloadSetVersion = installedWorkloadSets.Keys.Aggregate((s1, s2) => WorkloadUtilities.VersionCompare(s1, s2) >= 0 ? s1 : s2);
                     _workloadSets[latestWorkloadSetVersion] = GCAction.Keep;
                     _verboseReporter.WriteLine($"GC: Keeping latest installed workload set version {latestWorkloadSetVersion}");
                 }