Make GetWindowsPowerShellModulePath compatible with multiple PS installations (#12280)

Add additional check for each component of PSModulePath (that is set for WinPS process) - if it is has pwsh.exe in the parent directory, then it is considered another PS Core installation and this location is also filtered out.

src/System.Management.Automation/engine/Modules/ModuleIntrinsics.cs

@@ -1234,7 +1234,7 @@ namespace System.Management.Automation
 
 #if !UNIX
         /// <summary>
-        /// Returns a PSModulePath suiteable for Windows PowerShell by removing this PowerShell's specific
+        /// Returns a PSModulePath suiteable for Windows PowerShell by removing PowerShell's specific
         /// paths from current PSModulePath.
         /// </summary>
         /// <returns>
@@ -1261,9 +1261,24 @@ namespace System.Management.Automation
             var modulePathList = new List<string>();
             foreach (var path in currentModulePath.Split(';'))
             {
-                if (!excludeModulePaths.Contains(path))
+                var trimmedPath = path.Trim();
+                if (!excludeModulePaths.Contains(trimmedPath))
                 {
-                    modulePathList.Add(path);
+                    // make sure this module path is Not part of other PS Core installation
+                    var possiblePwshDir = Path.GetDirectoryName(trimmedPath);
+
+                    if (string.IsNullOrEmpty(possiblePwshDir))
+                    {
+                        // i.e. module dir is in the drive root
+                        modulePathList.Add(trimmedPath);
+                    }
+                    else
+                    {
+                        if (!File.Exists(Path.Combine(possiblePwshDir, "pwsh.dll")))
+                        {
+                            modulePathList.Add(trimmedPath);
+                        }
+                    }
                 }
             }
 

test/powershell/Modules/Microsoft.PowerShell.Core/CompatiblePSEditions.Module.Tests.ps1

@@ -646,6 +646,10 @@ Describe "PSModulePath changes interacting with other PowerShell processes" -Tag
             $errors | Should -Be $null
         }
 
+        It "Allows Windows PowerShell subprocesses to load WinPS version of `$PSHOME modules" {
+            powershell.exe -Command "Get-ChildItem | Out-Null;(Get-Module Microsoft.PowerShell.Management).Path" | Should -BeLike "*system32*"
+        }
+
         It "Allows PowerShell subprocesses to call core modules" {
             $errors = & $pwsh -Command "Get-ChildItem" 2>&1 | Where-Object { $_ -is [System.Management.Automation.ErrorRecord] }
             $errors | Should -Be $null