fix: rclone receiving SIGINT prematurely on Windows causing restic hang forever

Co-authored-by: greatroar <61184462+greatroar@users.noreply.github.com>

changelog/unreleased/issue-3601

@@ -0,0 +1,11 @@
+Bugfix: Fix rclone backend prematurely exiting when receiving SIGINT on Windows
+
+On Windows, Restic now start the rclone process detached from the
+restic console (similar to starting processes on a new process
+group on Linux). Therefore, when Ctrl+C is pressed on the console
+where restic runs, restic could gracefully clean up using clone,
+and rclone won't exit prematurely leading to restic hanging up with
+"stdio pipes closed" errors.
+
+https://github.com/restic/restic/issue/3601
+https://github.com/restic/restic/pull/3602

internal/backend/foreground_windows.go

@@ -2,12 +2,16 @@ package backend
 
 import (
 	"os/exec"
+	"syscall"
 
 	"github.com/restic/restic/internal/errors"
+	"golang.org/x/sys/windows"
 )
 
 func startForeground(cmd *exec.Cmd) (bg func() error, err error) {
 	// just start the process and hope for the best
+	cmd.SysProcAttr = &syscall.SysProcAttr{}
+	cmd.SysProcAttr.CreationFlags = windows.DETACHED_PROCESS
 	err = cmd.Start()
 	if err != nil {
 		return nil, errors.Wrap(err, "cmd.Start")