fix var init

Signed-off-by: zackzhangkai <zhangkaiamm@gmail.com>

main.go

@@ -169,7 +169,7 @@ func main() {
 			// no args, or interactive... read from stdin
 			// this is mainly for replacing text in vim
 			fi, _ := os.Stdin.Stat()
-			inputIsFromPipe = (fi.Mode() & os.ModeCharDevice) == 0
+			inputIsFromPipe := (fi.Mode() & os.ModeCharDevice) == 0
 			if len(args) == 0 && !PromptMode && inputIsFromPipe {
 				reader := bufio.NewReader(os.Stdin)
 				var buf bytes.Buffer