Harden Windows deferred update wait

src/bin/dosh-client.rs

@@ -4809,7 +4809,12 @@ fn windows_deferred_update_script(parent_pid: u32, installer_script: &str) -> St
     format!(
         "$ErrorActionPreference='Stop';\
          $ProgressPreference='SilentlyContinue';\
-         while (Get-Process -Id {parent_pid} -ErrorAction SilentlyContinue) {{ \
+         $parent=Get-Process -Id {parent_pid} -ErrorAction SilentlyContinue;\
+         $parentStart=if ($parent) {{ $parent.StartTime }} else {{ $null }};\
+         while ($true) {{ \
+             $current=Get-Process -Id {parent_pid} -ErrorAction SilentlyContinue;\
+             if (-not $current) {{ break }};\
+             if ($parentStart -and $current.StartTime -ne $parentStart) {{ break }};\
              Start-Sleep -Milliseconds 100 \
          }};\
          {installer_script}"
@@ -13172,6 +13177,15 @@ mod tests {
         );
         let deferred = windows_deferred_update_script(4242, &installer);
         assert!(deferred.contains("Get-Process -Id 4242 -ErrorAction SilentlyContinue"));
+        assert!(
+            deferred.contains("$parentStart=if ($parent) { $parent.StartTime } else { $null }")
+        );
+        assert!(deferred.contains("$current=Get-Process -Id 4242 -ErrorAction SilentlyContinue"));
+        assert!(deferred.contains("if (-not $current) { break }"));
+        assert!(
+            deferred
+                .contains("if ($parentStart -and $current.StartTime -ne $parentStart) { break }")
+        );
         assert!(deferred.contains("Start-Sleep -Milliseconds 100"));
         assert!(
             deferred.contains(
@@ -13179,7 +13193,7 @@ mod tests {
             )
         );
         assert!(
-            deferred.find("Get-Process -Id 4242").unwrap()
+            deferred.find("$parentStart").unwrap()
                 < deferred.find("irm 'https://git.palav.dev").unwrap()
         );
     }