dwim: take the scan flags (closes #162) (#193)

internal/sfdupes/scan_test.go

@@ -2196,7 +2196,7 @@ func TestScanHashWriteFailureUnwindsPool(t *testing.T) {
 	var stderr bytes.Buffer
 
 	code := run([]string{
-		cmdScan, "--workers", strconv.Itoa(hashLeakWorkers), dir,
+		cmdScan, workersFlag, strconv.Itoa(hashLeakWorkers), dir,
 	}, io.Discard, &stderr)
 	if code != exitFatal {
 		t.Fatalf("run(scan) = %d, want %d; stderr: %s",