Merge pull request #1747: UpgradeVerb: write deprecation notice

We removed the old upgrader in #1746 but delayed creating its replacement.

The plan was to use `winget upgrade`, but it is only experimental right now. Further, we would need to use `winget list` to determine if we needed `winget install` instead, and `winget list` is also experimental. The tool needs to mature more before we can create a dependency on it.

Instead, warn a user that tries to upgrade with `gvfs upgrade` that this CLI is no longer supported and instead point them to the repository's README which can help with the latest update.

GVFS/GVFS/CommandLine/UpgradeVerb.cs

@@ -1,41 +1,15 @@
 using CommandLine;
-using GVFS.Common;
-using GVFS.Common.FileSystem;
-using GVFS.Common.Tracing;
 using System;
-using System.Diagnostics;
-using System.IO;
 
 namespace GVFS.CommandLine
 {
     [Verb(UpgradeVerbName, HelpText = "Checks for new GVFS release, downloads and installs it when available.")]
     public class UpgradeVerb : GVFSVerb.ForNoEnlistment
     {
         private const string UpgradeVerbName = "upgrade";
-        private const string DryRunOption = "--dry-run";
-        private const string NoVerifyOption = "--no-verify";
-        private const string ConfirmOption = "--confirm";
-
-        private ITracer tracer;
-        private PhysicalFileSystem fileSystem;
-        private ProcessLauncher processLauncher;
-
-        public UpgradeVerb(
-            ITracer tracer,
-            PhysicalFileSystem fileSystem,
-            ProcessLauncher processWrapper,
-            TextWriter output)
-        {
-            this.tracer = tracer;
-            this.fileSystem = fileSystem;
-            this.processLauncher = processWrapper;
-            this.Output = output;
-        }
 
         public UpgradeVerb()
         {
-            this.fileSystem = new PhysicalFileSystem();
-            this.processLauncher = new ProcessLauncher();
             this.Output = Console.Out;
         }
 
@@ -67,56 +41,7 @@ protected override string VerbName
 
         public override void Execute()
         {
-            this.ReportErrorAndExit(this.tracer, ReturnCode.GenericError, "failed to upgrade");
-        }
-
-        public class ProcessLauncher
-        {
-            public ProcessLauncher()
-            {
-                this.Process = new Process();
-            }
-
-            public Process Process { get; private set; }
-
-            public virtual bool HasExited
-            {
-                get { return this.Process.HasExited; }
-            }
-
-            public virtual int ExitCode
-            {
-                get { return this.Process.ExitCode; }
-            }
-
-            public virtual void WaitForExit()
-            {
-                this.Process.WaitForExit();
-            }
-
-            public virtual bool TryStart(string path, string args, bool useShellExecute, out Exception exception)
-            {
-                this.Process.StartInfo = new ProcessStartInfo(path)
-                {
-                    UseShellExecute = useShellExecute,
-                    WorkingDirectory = Environment.SystemDirectory,
-                    WindowStyle = ProcessWindowStyle.Normal,
-                    Arguments = args
-                };
-
-                exception = null;
-
-                try
-                {
-                    return this.Process.Start();
-                }
-                catch (Exception ex)
-                {
-                    exception = ex;
-                }
-
-                return false;
-            }
+            Console.Error.WriteLine("'gvfs upgrade' is no longer supported. Visit https://github.com/microsoft/vfsforgit for the latest install/upgrade instructions.");
         }
     }
 }