`capacify' for `mrb_str_new_capa` should not be `0`.
MODIFY
src/variable.c
src/variable.c
@@ -1108,7 +1108,7 @@ mrb_class_find_path(mrb_state *mrb, struct RClass *c)
name = find_class_sym(mrb, mrb_class_ptr(outer), c);
if (name == 0) return mrb_nil_value();
str = mrb_class_name(mrb, mrb_class_ptr(outer));
- path = mrb_str_new_capa(mrb, 0);
+ path = mrb_str_new_capa(mrb, 40);
mrb_str_cat_cstr(mrb, path, str);
mrb_str_cat_cstr(mrb, path, "::");

`capacify' for `mrb_str_new_capa` should not be `0`.