patchbuiltin/branch.c: Use ALLOC_GROW instead of alloc_nr and xrealloc.

diff --git a/builtin/branch.c b/builtin/branch.c
index 807355a..7f34fad 100644
--- a/builtin/branch.c
+++ b/builtin/branch.c
@@ -314,11 +314,7 @@ static int append_ref(const char *refname, const unsigned char *sha1, int flags,
 	}
 
 	/* Resize buffer */
-	if (ref_list->index >= ref_list->alloc) {
-		ref_list->alloc = alloc_nr(ref_list->alloc);
-		ref_list->list = xrealloc(ref_list->list,
-				ref_list->alloc * sizeof(struct ref_item));
-	}
+	ALLOC_GROW(ref_list->list, ref_list->index + 1, ref_list->alloc);
 
 	/* Record the new item */
 	newitem = &(ref_list->list[ref_list->index++]);