[ruby/irb] Suppress "shadowing outer" warning

https://github.com/ruby/irb/commit/8b83fbef69

lib/irb/ruby-lex.rb

@@ -557,7 +557,7 @@ class RubyLex
         end_type << :on_regexp_end
       when :on_symbeg
         acceptable_single_tokens = %i{on_ident on_const on_op on_cvar on_ivar on_gvar on_kw}
-        if (i + 1) < tokens.size and acceptable_single_tokens.all?{ |t| tokens[i + 1][1] != t }
+        if (i + 1) < tokens.size and acceptable_single_tokens.all?{ |st| tokens[i + 1][1] != st }
           start_token << t
           end_type << :on_tstring_end
         end