bisect.c: reduce scope of variable

Signed-off-by: Elia Pinto <gitter.spiros@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/bisect.c b/bisect.c
index 1e46a4f..c718249 100644
--- a/bisect.c
+++ b/bisect.c
@@ -685,7 +685,6 @@
 
 static int bisect_checkout(char *bisect_rev_hex, int no_checkout)
 {
-	int res;
 
 	mark_expected_rev(bisect_rev_hex);
 
@@ -696,6 +695,7 @@
 			die("update-ref --no-deref HEAD failed on %s",
 			    bisect_rev_hex);
 	} else {
+		int res;
 		res = run_command_v_opt(argv_checkout, RUN_GIT_CMD);
 		if (res)
 			exit(res);