Rest source update issue

Brief description of your issue

Even though source is not avaiable currently, winget reports update done.

Steps to reproduce

• Add custome rest source winget source add -n rest-source -t "Microsoft.Rest" -a https://winget.example.com/
• update the source
• Turn down the app running rest source
• update the source

Expected behavior

Update the source, report if it encounter the error

Actual behavior

Reporting success message but in fact it was not.

Source list

$ winget source list
Name    Argument
-----------------------------------------------------
puvvadi https://winget.local.puvvadi.net/wg/
msstore https://storeedgefd.dsx.mp.microsoft.com/v9.0
winget  https://cdn.winget.microsoft.com/cache

Winget source update

$ winget source update
Updating all sources...
Updating source: puvvadi...
Done
Updating source: msstore...
Done
Updating source: winget...
Done

connection test

Invoke-RestMethod -Uri https://winget.local.puvvadi.net/wg/
Invoke-RestMethod: No such host is known.

Winget log

2023-11-04 14:02:07.041 [CORE] WinGet, version [1.6.2771], activity [{50BC38BD-7E81-4F8B-A1E2-2EDAF20C49A1}]
2023-11-04 14:02:07.041 [CORE] OS: Windows.Desktop v10.0.22621.2428
2023-11-04 14:02:07.041 [CORE] Command line Args: "C:\Users\kd\AppData\Local\Microsoft\WindowsApps\winget.exe" source update
2023-11-04 14:02:07.041 [CORE] Package: Microsoft.DesktopAppInstaller v1.21.2771.0
2023-11-04 14:02:07.041 [CORE] IsCOMCall:0; Caller: winget-cli
2023-11-04 14:02:07.053 [CLI ] WinGet invoked with arguments: 'source' 'update'
2023-11-04 14:02:07.053 [CLI ] Found subcommand: source
2023-11-04 14:02:07.053 [CLI ] Found subcommand: update
2023-11-04 14:02:07.053 [CLI ] Leaf command to execute: root:source:update
2023-11-04 14:02:07.053 [CLI ] Executing command: update
2023-11-04 14:02:07.090 [REPO] Named source requested, found: puvvadi
2023-11-04 14:02:07.092 [REPO] Named source to be updated, found: puvvadi
2023-11-04 14:02:07.197 [REPO] Named source requested, found: msstore
2023-11-04 14:02:07.203 [REPO] Named source to be updated, found: msstore
2023-11-04 14:02:07.304 [REPO] Named source requested, found: winget
2023-11-04 14:02:07.307 [REPO] Named source to be updated, found: winget
2023-11-04 14:02:07.329 [CORE] Examining extension: PFN = Microsoft.Winget.Source_8wekyb3d8bbwe, ID = IndexDB
2023-11-04 14:02:07.329 [CORE] Found matching extension.
2023-11-04 14:02:07.662 [CLI ] Leaf command succeeded: root:source:update

Rest source /information end point

{
  "Data": {
    "ServerSupportedVersions": [
      "1.4.0",
      "1.5.0"
    ],
    "SourceIdentifier": "puvvadi"
  }
}

Environment

Windows Package Manager v1.6.2771
Copyright (c) Microsoft Corporation. All rights reserved.

Windows: Windows.Desktop v10.0.22621.2428
System Architecture: X64
Package: Microsoft.DesktopAppInstaller v1.21.2771.0

Start by reproducing winget source update with a custom Microsoft.Rest source, then inspect the source-update path using the provided log and /information response. Confirm that stopping the REST service produces an error instead of Done; the issue is complete when the failure is reported for the unavailable source.