test/ruby/test_hash.rb: suppress syntax warning

Avoid "ambiguous first argument; put parentheses or a space even after
`-' operator" warning in assert_in_out_err. Fixes r56992.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@56993 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/ruby/test_hash.rb

@@ -1334,7 +1334,7 @@ class TestHash < Test::Unit::TestCase
   def assert_hash_random(obj, dump = obj.inspect)
     a = [obj.hash.to_s]
     3.times {
-      assert_in_out_err(["-e", "print #{dump}.hash"], "") do |r, e|
+      assert_in_out_err(["-e", "print (#{dump}).hash"], "") do |r, e|
         a += r
         assert_equal([], e)
       end