feat(scoop-update): Support scoop update scoop (#4992)

Author: chawyehsu

CHANGELOG.md

@@ -3,6 +3,7 @@
 ### Features
 
 - **core:** Add `Get-Encoding` function to fix missing webclient encoding ([#4956](https://github.com/ScoopInstaller/Scoop/issues/4956))
+- **scoop-update:** Support `scoop update scoop` ([#4992](https://github.com/ScoopInstaller/Scoop/issues/4992))
 - **scoop-virustotal:** Migrate to virustotal api v3, improve flows, and ouput powershell objects ([#4983](https://github.com/ScoopInstaller/Scoop/pull/4983))
 - **scoop-hold,scoop-unhold:** Support `-g`/`--global` flag ([#4991](https://github.com/ScoopInstaller/Scoop/issues/4991))
 

lib/core.ps1

@@ -855,7 +855,7 @@ function Confirm-InstallationStatus {
         $Global
     )
     $Installed = @()
-    $Apps | Select-Object -Unique | Where-Object { $_.Name -ne 'scoop' } | ForEach-Object {
+    $Apps | Select-Object -Unique | Where-Object { $_ -ne 'scoop' } | ForEach-Object {
         $App, $null, $null = parse_app $_
         if ($Global) {
             if (Test-Path (appdir $App $true)) {

libexec/scoop-update.ps1

@@ -306,19 +306,24 @@ if (-not ($apps -or $all)) {
         'ERROR: You need admin rights to update global apps.'; exit 1
     }
 
-    if (is_scoop_outdated) {
-        update_scoop
-    }
     $outdated = @()
+    $updateScoop = $null -ne ($apps | Where-Object { $_ -eq 'scoop' }) -or (is_scoop_outdated)
+    $apps = $apps | Where-Object { $_ -ne 'scoop' }
     $apps_param = $apps
 
+    if ($updateScoop) {
+        update_scoop
+    }
+
     if ($apps_param -eq '*' -or $all) {
         $apps = applist (installed_apps $false) $false
         if ($global) {
             $apps += applist (installed_apps $true) $true
         }
     } else {
-        $apps = Confirm-InstallationStatus $apps_param -Global:$global
+        if ($apps_param) {
+            $apps = Confirm-InstallationStatus $apps_param -Global:$global
+        }
     }
     if ($apps) {
         $apps | ForEach-Object {